Analysis of Antecedents and Their Influences on Sustainable Public Procurement: A Structural Equation Modeling Approach

Abstract

Public procurement (PP) helps promote sustainable development and plays a strategic role in the economy of countries. The general objective of this research is to analyze the main antecedents, their influences, and challenges in the sustainable acquisition and contracting of goods and services by public institutions through a quantitative and statistical approach based on the development of improvement proposals. The methodological aspects of this paper permeate the conceptual stage on the frontier of knowledge of antecedents in sustainable public procurement (SPP), which includes actors, strategies, barriers, and purposes. A conceptual framework and hypotheses arising from theory were developed and a survey was conducted among employees of higher education institutions (HEIs) in Brazil, and with structural equation modeling (SEM) an integrated model in sustainable public procurement (SPP) was structured. The results of the research validate the constructs in SPP and highlight the causal relationships between them. It empirically validates an integrated model in SPP and the hypothesis tests. The constructs actors, strategies, and purposes significantly influence sustainability improvements in PP, demonstrating their strategic importance, and barriers negatively influence purposes, demonstrating the importance of knowledge on the topic to mitigate their adverse effects. This research offers insights for managers, policymakers, and researchers in SPP in the search for a more systemic view of the process and to improve sustainability indices in public procurement.

1. Introduction

The discussion of public procurement (PP) has been gaining momentum in both national and international scenarios, particularly in recent years; the growing discussions on the Sustainable Development Goals (SDGs) are fueling this process. This growth enables the strategic role of PP in the economies of countries, with PP representing up to 12% of the gross domestic product (GDP) [1,2].

In the European Union, public bodies are the largest consumers, whose spending on PP represents between 16% and 19% of GDP [3,4,5]. In Japan, the percentage of spending on PP represents 17.5% of the country’s GDP, and in China, this spending accounts for up to 27% of the country’s GDP [6]. In Brazil, some studies indicate that such spending comprises 12% of GDP [7,8].

Sustainable public procurement (SPP) utilizes governments’ purchasing power to promote sustainable consumption and production [9]. The education system has recently been identified as a key opportunity to drive social change towards more sustainable behaviors [10]. Higher education institutions (HEIs) are evaluated based on their contribution to achieving the Sustainable Development Goals (SDGs) in all their activities, not just in education and research, and thus seek to adopt practices that make them leaders in sustainable development [11].

The mission and vision of HEIs are committed to sustainable development and influencing regional and global development, such as mitigating greenhouse gas emissions. Considering higher education institutions (HEIs) as a complex system, sustainable development must be based on holistic and systemic thinking and action, requiring the sharing of information among professors, students, and technical administrative staff [12,13].

SPP is a crucial means of promoting sustainability and fostering ethics in public service through efficient spending and the preservation of institutional values, including transparency, citizen participation, and the prevention of corruption [12].

Public sector organizations are key players in the urgent transition to more sustainable societies. SPP is emphasized as a governance tool to address pressing social challenges and create value beyond the interests of the purchasing organization [4]. As a policy tool, SPP is market-based and demand-driven. Its potential to support the achievement of the SDGs depends on a regulatory framework that is attractive to both buyers and suppliers [4].

Although regulatory requirements emphasize the inclusion of sustainability in procurement, the adoption of such practices and measures is still slow. Strict legal frameworks are essential to ensure equity, but they conflict with internal sustainability initiatives that require more flexibility and innovation [13].

Despite its strategic importance, sustainability in PP remains an underexplored topic in academic research. Most studies focus on developed countries, particularly in Europe, and primarily address environmental issues [4,14]. A notable disparity exists in sustainability perspectives between developed countries, which tend to emphasize ecological problems, and developing countries, where the focus is often on social concerns [15,16,17].

It has become clear that public higher education institutions (HEIs) face similar challenges to other public organizations in implementing strategic planning and performance (SPP). With the proper measures in place, many of the obstacles can be turned into opportunities, thereby increasing the ability of HEIs to act as promoters of SPP. Given the impossibility of directly influencing the external constraints imposed by PP law, HEIs need to find solutions that enable the introduction of sustainability into the procurement process through an SPP policy [13].

Given these considerations, in line with the existing gap in scientific articles on the subject, the difference in the vision of sustainability between developed and developing countries, and the low percentage of sustainability in public procurement, this study aims to help answer these questions. As an objective, this research seeks to identify the primary antecedents of SPP, their influences, and challenges in the sustainable acquisition of goods and services in higher education institutions (HEIs) through a quantitative and statistical approach, informed by the development of improvement proposals. As a result, this study presents a conceptual framework of the antecedents of SPP. It proposes an integrated model, based on the structural equation modeling method, to address challenges and enhance sustainability indices in the acquisition of goods and services by higher education institutions (HEIs).

This research contributes to the literature by considering the global importance of public procurement and the significance of the theme for sustainable development, including that of higher education institutions (HEIs). By identifying and analyzing the antecedents in SPP and their characteristics and influences through the proposed model, it suggests improvement proposals to increase sustainability criteria in public procurement and contracting significantly.

This article is divided into six sections, starting with this introduction. Section 2 presents the theoretical framework and research hypothesis. Section 3 details the research methodology. Section 4 provides the results and discussion. Section 5 concludes with final remarks and an overview of future trends.

2. Theoretical Framework and Research Hypotheses

2.1. Overview of Sustainable Public Procurement

To analyze the frontier of knowledge on this subject, a survey was conducted in January 2022 to identify existing systematic literature reviews (SLRs) on the topic of SPP in the scientific databases Scopus and Web of Science. As a result, most studies specifically analyzed green public procurement, while other studies focused on electronic public procurement tools or their use in specific sectors, such as food or construction. Other studies focused on the barriers to implementation.

Considering the limitations of existing research, a systematic literature review (SLR) for SPP was conducted with a more comprehensive approach to identify the antecedents in SPP and answer the following research question: what are the antecedents in SPP and their interactions for the development of sustainable aspects in the supply of products and services? For the second research question, focusing on SPP for HEIs, a new round was conducted with the inclusion of an additional string.

For the first round of the RSL, the following strings were used: (“public procurement” OR “government procurement”) AND (“sustainable” OR “sustainability” OR “green”) AND (“supply chain”), in the Scopus and Web of Science databases, considering the period from 2000 to 2022. For the second round, considering the period from 2000 to 2025, the following strings were used: (“public procurement” OR “government procurement”) AND (“sustainable” OR “sustainability” OR “green”) AND (“Higher Education Institutions”). The authors reviewed all available rounds, incorporating more recent studies to deepen their understanding of the current state of knowledge on the topic.

The review enabled us to broaden our understanding of the existing literature on the topic, identify the antecedents in SPP and their interactions, and focus on the subject in higher education institutions (HEIs).

Before presenting the antecedents in SPP and the research hypotheses, it is essential to understand the concept of SPP and the current scenario regarding the topic, adopting a unique approach for higher education institutions (HEIs). The term initially introduced was green purchasing, which was defined by the European Commission in 2008, focusing on environmentally sustainable purchasing and promoting a focus on the product life cycle. Europe’s primary focus remains this way [16,18].

The focus of SPP expands the previously exclusively environmental aspects to encompass social and economic factors. Despite the widespread use of the definition provided by the European Commission, authors state that the concept remains vague [14,19], as it can vary between countries and organizations, and therefore its use and impact cannot be easily measured [20]. When considering the strategic role of procurement, research indicates that the public sector has received little academic attention despite representing a significant share of government spending [4,21]. This situation may have occurred due to the fear of discussing strategic and innovative practices under restrictive and conservative legislation [22]. Although clear actions toward SPP are still lacking, it is encouraging that the public universities analyzed have committed to the UN Sustainable Development Goals. Due to increasing government spending, SPP has become a crucial component of sustainable development [10].

Most emerging countries, including China, still lack the necessary infrastructure to support sustainability in the public sector [15]. In Brazil, SPP represents approximately 1% of public acquisitions, and measuring its impact is a challenge highlighted by researchers, despite the existence of a strong legal framework [23,24]. In Canada, research indicates a superficial level of inclusion of sustainability in acquisitions, as only 12% of the bids evaluated included sustainable criteria, with weights of up to 15% allocated to sustainability [25].

The theoretical basis that underpins the constructs, their relationships, and the research hypotheses is presented below.

2.2. Actors in Sustainable Public Procurement (ASPP)

The authors conducted a systematic literature review, and three primary actors in SPP were identified: (i) buyers—public institutions that aim to provide citizens with more sustainable products and services by increasing efficiency, reducing transaction costs, ensuring transparency in resource use, setting requirements, managing financial resources, and selecting suppliers; (ii) suppliers—entities meeting SPP demands, seeking to establish long-term relationships, ensure fair competition, and increase productivity; and (iii) promoters—regulatory bodies, non-governmental organizations (NGOs), and public authorities that advocate for sustainable procurement policies to encourage sustainable business models and push other actors to adopt practices that promote social inclusion, gender equality, ethics, and governance [20,26].

In Brazil, the role of promoters is considered crucial and highly impactful, especially in public authorities such as the Public Prosecutor’s Office, the Federal Comptroller General, and the Office of the Attorney General, which oversees the enforcement of existing laws [27]. In the SPP system, various actors play a central role, influencing and being influenced by the outcomes of sustainability practices in public contracts. The state and its representatives often navigate multiple and sometimes conflicting interests among stakeholders [1,28].

Secondary stakeholders are essential for establishing an institutional and regulatory–legal environment conducive to the implementation of SPP, developing macro guidelines at a global and regional level, such as the United Nations, the Southern Common Market (Mercosur), support organizations for micro and small businesses, and the United Nations Environment Program (UNEP) [27].

In higher education institutions (HEIs), additional stakeholders have been added, including academics and non-academics, who must possess a sustainable mindset, commitment, and in-depth knowledge to determine the sustainable characteristics of products and services, ensuring that they are not considered discriminatory or harmful in competition [13].

HEI students must receive an education focused on sustainability, considering that they will be future leaders and key participants in the circular economy. Faculty, staff, and students must be involved in interdisciplinary projects at all levels of society to support the SPP. Dependence on political will is a significant constraint for actors in SPP [14]. Studies from the Netherlands indicate that senior management and those responsible for the budget are the most relevant actors in SPP, being responsible for essential factors such as management support, information, communication, and training, the latter being considered a critical factor [29].

2.3. Strategies in Sustainable Public Procurement (SSPP)

Researchers highlight strategies related to senior management support, the scale benefits of collaborative purchasing, and the lowest price criterion, which is evidenced in more than 70% of acquisitions [30]. Requirements related to performance and environmental impact are the most frequently found in the literature, and the specific legislation on the subject demonstrates the importance of state regulatory intervention in disseminating information on sustainable products [1,31].

Research suggests strategies related to defining criteria for bidding notices, including aspects that favor the circular economy [30]. Thus, from the acquisition to the disposal or reuse of the product, a study by [32] highlights that, in the European Union, 38% of contracts include green criteria, and [33] highlights the verification of 73% of green criteria in bids and 30% in contracts in Tuscany (Italy).

In the social dimension, researchers highlight the quest to promote local production sustainably, encouraging the management of this specific chain, with a focus on fostering family farming and socially responsible contracting, with criteria that facilitate the participation of small and medium-sized enterprises (SMEs), as an example of the strategies of Latin American and Caribbean countries, related to local production, with the strengthening of family farming [26,34].

In an integrated manner, the strategies outlined in the literature emphasize the incorporation of technological and innovative solutions into the project, as well as the development of partnerships with suppliers [35]. Researchers emphasize the need for regulation and a unified framework for addressing the issue, as observed in European Union countries [4,16]. Procurement policies, including environmental considerations, reverse logistics, sustainability criteria in bidding processes, and the promotion of functional specifications, drive innovation and ensure the adoption of environmentally friendly products and services [1].

Food services in higher education institutions (HEIs) play a key role in promoting student participation and progression (SPP). Food consumption is responsible for 20% to 30% of greenhouse gas emissions in Western countries. Sustainable practices are identified on the campuses of HEIs, including concerns about transportation, energy, water, landscaping, and waste [10].

Research in higher education institutions (HEIs) has identified that strategies related to employee competence, training, financial aspects, management commitment, government laws and regulations, the unavailability of green products, supplier capacity, and third-party pressure have a direct relationship with sustainable procurement practices (SPPs). On the other hand, the ineffectiveness and price of green products have an insignificant direct relationship with sustainability in public procurement [15].

Studies show that it is challenging to measure social criteria in tenders, whereas environmental impacts are more advanced and quantifiable. Verifying compliance with all requirements is a bottleneck in SPP [14,32,36]. Countries such as Sweden, Denmark, Italy, and Scotland face the challenge of interpreting European Union regulations on public procurement, as well as adapting strategies to the local context and calibrating food supply and demand [14].

2.4. Purposes in Sustainable Public Procurement (PSPP)

The primary research does not indicate quantifiable and precise results on implementing SPP. It points to bottlenecks in measuring impacts. Researchers have identified purposes when implementing SPP, such as those focused on the economic dimension, including managing the trade-off between sustainability costs and acquisitions [4,37]. In the environmental dimension, researchers have identified possibilities for reducing greenhouse gases with SPP, and countries are actively learning and developing strategies to enhance their carbon reduction ambitions. The authors emphasized the purpose of creating more circular business models, focusing on efficiency, the preservation of natural resources, and the mitigation of impacts [13,30,38].

The inclusion of sustainable aspects depends on the reality of each country. Thus, studies by [16] demonstrate that, in African countries, the social dimension is more effective in minimizing poverty and social inequalities. In contrast, in the European Union, the environmental dimension is more evident in public procurement.

In the integrated context, researchers examined the roles of individuals’ beliefs, religion, and sense of humanity as influencers, highlighting that public institutions actively seek organizational learning through SPP [33,39]. In short, characteristics concerning expanding business, influencing more sustainable behaviors, fostering strategic partnerships, and meeting society’s demand for more sustainable products and services are required [20,26].

Specific studies in higher education institutions (HEIs) indicate that leadership approach models increase economic benefits, mitigate risks, and create transformative change in purchasing management processes, contributing to broader social and environmental objectives [13]. SPP plays a crucial role in the agroecological transition, driven by local development initiatives, in the sustainable transformation of food systems and in achieving the SDGs [10].

2.5. Barriers in Sustainable Public Procurement (BSPP)

SPP is still in the process of consolidation. Public institutions that implement sustainable procurement practices can achieve significant advantages and benefits, but they also face challenges and obstacles. For improvements in SPP, it is essential to adopt sustainability as an organizational strategy integrated across all levels of the organization [13,31].

Among the barriers or obstacles to implementing SPP, researchers highlight main challenges: (i) lack of information about sustainable products, (ii) financial constraints, and (iii) insufficient training and knowledge among employees involved in public procurement [1,31]. Challenges were also identified in the following areas: long-term planning, methods for measuring sustainability, organizational culture, government incentives, senior management support, and the perception that sustainable products might reduce market competition [7,8,13].

IES highlights that the cost of local and organic products, especially when compared to the globalized agribusiness, the profit margin in business throughout the production and distribution chain, and monitoring sustainability after the contract is awarded are essential challenges for SPP in demonstrating concern for the environmental impact of the food system and commitment to the SDGs [10]. Cultural transformation is highlighted as the primary challenge for shifting the SPP paradigm to a systemic, collaborative, and cooperative vision [12].

Emerging countries often lack the necessary infrastructure to support sustainability in the public sector, as evidenced by research in China, where all procurement notices adhere to traditional models without incorporating sustainability criteria [15]. In Brazil, there is a need for a paradigm shift and new social attitudes supported by education that promotes critical thinking and the transformative power of sustainability ethics [13,40]. In this context, SPPs emerge as a tool to promote sustainable practices that improve both the behavior and the image of public institutions through holistic and systemic thinking and actions [13].

2.6. Sustainability in Public Procurement (SPP)

Studies indicate that the topic of SPP still receives little attention from researchers [22], and that there are challenges in measuring sustainability in public procurement and its impacts [7,8]. Among the benefits of SPP, key research highlights aspects related to the external and internal motivations of organizations, including (i) reduction in harmful emissions and waste generation; (ii) improvement in air and water quality; (iii) improvement in working conditions; (iv) improvement in the condition of disadvantaged groups; (v) improvement in the quality of life of society; and (vi) improvement in the ethical behavior of suppliers/contractors. However, their impacts are usually long-term, and combined with the lack of information about the actual environmental impact and the difficulty in finding suppliers and defining purchasing guidelines, the barriers to public procurement are highlighted [1,31,33].

The need for a paradigm shift in public procurement and the search for factors that influence sustainable practices demonstrate the importance of disseminating the topic and sharing information. Research on the subject indicates the importance of improving studies on the perception of costs and benefits, the availability of sustainable products and services, organizational pressure, familiarity with policies and regulations, and the actions and beliefs of individuals within organizations [1,13,33].

The literature points out the main reasons why SPP has not yet become a practice at the organizational level, namely (i) it is considered resource-intensive and costly [13]; (ii) the tangible benefits are still uncertain [41]; (iii) there is a lack of strategic alignment with technical terms [42]; (iv) it depends on political factors that allow a favorable structure [13,43]; and (v) it tends to approach sustainability in a fragmented way disconnected from the organizational strategy [44].

2.7. Research Hypotheses

According to the identification and analysis of the constructs related to the antecedents in SPP, this research highlights the hypotheses of influence between the constructs.

H1. 

Actors positively influence strategies in SPP.

Issues related to sustainability require not only political and technical measures but also a new ethical sensitivity, new values, other forms of relationship with nature, and new patterns of production and consumption. Research indicates an increase in conscious consumers who drive market innovation and demand more collaborative and transparent practices [12].

In this context, the research emphasizes the importance of incorporating the perspectives of other stakeholders on the various dimensions of sustainability in SPP. This approach aims to promote ethical practices in public service by ensuring efficient spending, upholding institutional values such as transparency and citizen participation, and strengthening anti-corruption measures [1,45].

Promoters, such as public authorities responsible for overseeing the implementation of current laws, including the Public Prosecutor’s Office and the Comptroller General of the Union, as is the case in Brazil, play a leading and highly impactful role in SPP strategies [27]. Suppliers and promoters who positively influence public procurement strategies, as evident in the greater emphasis on environmental aspects linked to food purchases by European articles [20,26,28], are already beginning to identify approaches related to social issues, such as strategies associated with promoting gender equity [46].

The state, in its role as a buyer and promoter of public policy, shapes strategies that drive SPP. Additionally, it helps foster a new consumer and producer market driven by public interest in protecting both the natural and human environment [4,7].

Research indicates that the level of stakeholder engagement and skills influences the search for appropriate measures that can enhance the capacity of higher education institutions (HEIs) to act as promoters of Sustainable Public Policy (SPP) [13]. Top management must be genuinely committed to sustainability and must support the efforts of middle management in pursuing sustainable strategies and goals [15].

By offering subsidies to companies that produce sustainable items, the government increases the number of suppliers available in the market, which helps reduce prices. Additionally, by inviting suppliers to participate in the purchasing process, management encourages relationship-based strategies [15].

Research in higher education institutions (HEIs) shows that promoting school feeding programs supports strategies related to crop diversification, agroecological production, and improved market access [47]. These programs also advance strategies related to gender equality by increasing women’s participation in agriculture, thereby contributing to the achievement of the Sustainable Development Goals (SDGs) [48].

H2. 

Strategies positively influence purposes in SPP.

Strategies in SPP, such as support from senior management, shared purchases, and promotion of local production, are linked to the purposes, results, and improvements in sustainability indicators in public procurement. However, strategies related to the lowest price are more valued, corresponding to 73.14% of the criteria addressed in the bids [30,33]. The search for purposes related to social aspects is present in various studies, with strategies associated with the participation of SMEs, including those owned by women, this being one of the UN’s Sustainable Development Goals [49], as well as strategies of countries in Latin America and the Caribbean, linked to the education and food procurement sector, promoting social and environmental aspects by encouraging local production, with the strengthening of family farming [34].

SPP strategies related to food purchasing and food services in HEIs represent an essential opportunity to promote sustainable eating behaviors [10]. Awareness and educational efforts stem from HEI strategies, including sustainability plans, improvements in contract notices, monitoring of contract specifications, and waste management. By implementing green policies, higher education institutions (HEIs) should take the lead in promoting sustainable development [10].

H3. 

Strategies positively influence barriers in SPP.

Strategies in SPP reduce barriers, such as those related to the dissemination of knowledge, through the creation of specialized boards on the subject and guides for sustainable contracting, which serve as relevant instruments for consultation, guidance, and promotion of legal certainty [1].

The main barrier identified in research on HEIs in Brazil is the investment in training, which is linked to a deficient culture, unfavorable economic policies, and the need to improve the systemic vision throughout the process. Thus, this demonstrates the need to expand strategies on this topic [12].

The concept of sustainability is applied throughout the life cycle of contracts in a systemic and integrated manner, optimizing resources. This model also includes shared purchasing, leveraging the expertise accumulated by different units, and minimizing barriers related to procedural costs [1,50].

H4. 

Barriers negatively influence purposes in SPP.

Barriers related to economic issues consider that SPPs utilize intensive and expensive resources with uncertain tangible benefits, which challenges their implementation in terms of technical and strategic alignment and, therefore, hinders their purposes [27]. Issues related to the lack of long-term planning, difficulties in measuring social and environmental impacts, inadequate training, and an organizational culture that hinders the development of new circular business models [30,38] make it challenging to provide quantifiable results and foster innovative circular business models.

Low public sector investments in distribution infrastructure, institutional complexity, and high costs for local producers hinder programs that support crop diversification, agroecological production, and increased market access, thereby contributing to food security. In Brazil, this potential is limited to only 10% of family farmers nationwide [47].

H5. 

Purposes positively influence sustainability in PP.

Considering the practical benefits of increased sustainability in public procurement, studies indicate that in the European Union, 38% of contracts include green criteria. For example, in the Tuscany region of Italy, 73% of green criteria were verified in bids and 30% in contracts [32,33]. Studies by Bulgarian higher education institutions (HEIs) indicate that policy-related purposes in SPP, with an internal leadership approach, can influence external constraints and facilitate the integration of sustainability into procurement processes [13].

To minimize barriers and increase the percentage of sustainability in acquisitions, a new governance model is proposed in the Federal Public Ministry (MPF) in Brazil, which results in a reduction of approximately 95% in procedural costs, a gain in scale of 30.38% about the estimated average price, and actual savings of the first five contracts of the system of 11.76% [51]. In Brazilian higher education institutions (HEIs), studies indicate that the Federal University of Bahia (UFBA) stands out in the region, being the first in volume and second in expenses with SPP. At UFBA, stakeholders consider only 1.71% of acquisitions sustainable, which accounts for 0.35% of the total amount spent. In the Federal Public Administration (FPA), the research indicates 0.75% of volume with SPSS and 0.21% of expenses [24]. Researchers highlight the need for improvements in SPP to address problems with failures in inspection and training forecasts, as well as a low percentage of sustainable bids, which account for less than 1% of public acquisitions in Brazil [23].

Figure 1 presents the conceptual framework based on the constructs and hypotheses of this research.

3. Method

This study can be characterized as a descriptive and quantitative research effort that aims to analyze the antecedents of SPP and its influence on higher education institutions and propose actions for improvement. For this purpose, the structural equation modeling (SEM) technique was employed, which enables the analysis of dependency relationships between observed and latent variables, as well as the interconnections between latent variables (constructs). Through confirmatory factor analysis (CFA), this technique enables the identification of relationships and influence paths between constructs [52,53].

The research sample was obtained randomly and non-probably [52], and the snowball technique was used for data collection, which is commonly employed in research involving specific groups. In this case, the groups targeted were managers, buyers, and main demanders of federal higher education institutions (HEIs) in Brazil [54,55]. Initially, groups of vice-rectors of administration of HEIs considered key informants were selected and invited to answer the questionnaire. We asked them to forward the document to other managers of related areas, as well as to their employees in the purchasing sector, and that the latter forward it to the main demanders of HEIs, thus progressively expanding the sample among the specific groups to understand perceptions, recurring patterns, and divergences on the topic of SPP [52,54].

It is essential to acknowledge the potential biases inherent in this sampling technique, including reliance on the initial network, limited representativeness of the broader population, and the likelihood of homogeneity among respondents. To mitigate their effects, the following strategies were implemented: (i) diversification of the initial network of participants, selecting key informants from different regions and HEIs; (ii) comparison of responses between groups from the regions; (iii) triangulation with data from the theoretical framework to verify their consistency; and (iv) perceptions from different hierarchical levels [54,56].

A quantitative methodology (survey) was used, with a descriptive approach, employing multivariate statistical techniques with descriptive analysis, confirmatory factor analysis (CFA) with the SPSS software (v. 21), and covariance-based structural equation modeling (CB-SEM) with the AMOS software (v. 21) to test, confirm the theory, and validate the conceptual framework [53].

The preparation of the research instrument followed systematic steps to ensure its validity and reliability. Initially, the questionnaire was prepared based on the systematic literature review (SLR) carried out on SPP. To ensure content validity, the instrument was submitted to the evaluation of six experts in the area of public administration and sustainability, as suggested by [57]. Based on this feedback, adjustments were made to the wording of certain items to enhance clarity. A pilot stage was then carried out with 43 respondents from HEIs, who had profiles similar to those in the final sample. This number was considered reasonable, corresponding to more than 10% of the expected final sample, and fell within the standards considered permissible, 30 to 50 respondents [57,58,59]. The responses were incorporated into the final sample, as no difficulties or invalid responses were identified. Statistical validation was conducted through confirmatory factor analysis (CFA) and the calculation of composite reliability (CR) and Cronbach’s alpha for each construct, according to criteria proposed by [59], thus ensuring the quality of the data and the robustness of the results obtained.

We collected data between November 2023 and November 2024, sending questionnaires by email to 26 vice-rectorates of administration in federal higher education institutions in Brazil, distributed across the country’s five regions, and requested them to be forwarded to buyers, managers, and main demanders. An electronic Google Forms questionnaire was created. The questionnaire (Appendix A) consists of 4 open-ended questions to diagnose the profile of the respondents, including questions related to the institution, position, sector of activity, and length of experience in public service, and 17 closed-ended questions, based on the SPP theory, with examples, to facilitate the understanding of the respondents, on a 5-point Likert scale, with 1 for completely disagree and 5 for completely agree. To facilitate understanding of certain concepts, practical examples were added to the questionnaire, which were validated in the pilot test. We also considered that the sample consisted of experienced employees in the area of sustainability, including managers, buyers, and teachers, and that by sending the questionnaire link, we informed them that we were available to clarify any doubts.

During data cleaning, no null responses were identified, nor were any observations far from the centroid based on the Mahalanobis Distance parameters [60]. The final sample consisted of 165 valid cases, and according to [61], the recommended minimum sample size is 50 for multivariate data analysis. For models with moderate relationships and up to seven constructs, a sample size of 150 to 200 cases is considered adequate. However, we recognize that, although the size is sufficient to detect relevant statistical effects, the statistical power may be limited in detecting small or subtle effects, which should be considered when interpreting the results. Generalization of the data to other public administration contexts should be performed with caution, considering the analysis was conducted on only a specific group, which may limit the external validity of the results [62]. To mitigate these limitations, future research can increase the number of respondents and include samples from different groups and sectors of public administration.

Initially, the combination of observable variables was constructed within their respective constructs based on the theoretical basis and confirmatory factor analysis (CFA). The following validation criteria were followed [52,63]:

(a) Index of normality and variability: (i) Z Score [−3 < Z < +3] [61,64]; (ii) Bartlett’s test of sphericity [61], p < 0.001 for each observable variable; (iii) kurtosis index using Mardia’s coefficient (>5) [65,66]; (iv) Pearson’s Coefficient of Skewness (values close to zero) [61,64]; (v) mean; and (vi) standard deviation.

(b) Confirmatory factor analysis (CFA) [61,63]: (i) Factor loadings (≥0.5); (ii) communality (≥0.5); (iii) Cronbach’s alpha (>0.7); (iv) Kaiser–Meyer–Olkin (KMO) (>0.5); and (v) composite reliability (>0.7) [67].

(c) Index of reliability: (i) Multicollinearity observed in Pearson’s correlation (>0.7) [52]; (ii) Average Variance Extracted (AVE)— convergent validity (CV) (>0.7) and discriminant validity (DV) (less than convergent validity) [67].

(d) To evaluate the hypotheses H1, H2, H3, H4, and H5, the following indexes were used: (i) Standardized Estimates (SEs) (SE values: less than 0.3—low intensity; between less than 0.3 and 0.5—moderate intensity; greater than 0.5—high intensity) [53,68], and (ii) significance level (p) index.

(e) We evaluate the model’s fit parameters to verify that the structural model aligns with the set of measured data [52,66,69,70,71]: (i) chi-square value of the estimated divided by degrees of freedom (DF) (≤5); (ii) Comparative Fit Index (CFI) (values close to 1.0); (iii) Normed Fit Index (NFI) (≥0.9); and (iv) Root Mean Squared Error of Approximation (RMSEA) (between 0.05 and 0.08). It is worth noting that the mode adjustment indices assess the quality of the structural model and indicate possibilities for improvement; however, they should not be used as a parameter for evaluating hypotheses.

For the analysis of the constructs and their variables, refer to

Table 1. Constructs and observable variables.

Constructs and Observable Variables (Appendix A)	References
Actors in SPP (ASPP) ASPP1; ASPP2; ASPP3	[16,20,26,27,33,38]
Strategies in SPP (SSPP) SSPP1; SSPP2; SSPP3; SSPP4; SSPP5	[20,30,33,34,35,38]
Purposes in SPP (PSPP) PSPP1; PSPP2; PSPP3	[30,38,39]
Barriers in SPP (BSPP) BSPP1; BSPP2; BSPP3; BSPP4; BSPP5; BSPP6; BSPP7	[7,31]
Sustainability in PP (SPP) SPP1; SPP2; SPP3	[20,35]

Source: Prepared by the authors.

, which lists the relevant literature references.

4. Results and Discussions

The questionnaire was addressed to buyers, managers, and main demanders of products and services from higher education institutions (HEIs) in Brazil and sent by email to the vice-rectorates of administration of the selected HEIs. The sample resulted from 165 complete responses. According to [61], the minimum recommended sample size for multivariate data analysis is 50. The sample presented the following data, divided by region of Brazil, as descriptive statistics: 70.30% from the southeast, 10.91% from the northeast, 10.30% from the central-west, 4.24% from the north, and 4.24% from the south. Regarding the positions of employees, the survey indicates that 46.67% are buyers and support staff, 17.57% are managers, and 35.76% are demanders. Despite the geographic concentration of the sample, with a predominance of respondents in the southeast region, which may introduce a regional bias, affecting the external validity and generalization of the results, we consider that the data maintained a methodological standardization, thus contributing to the comparability between the responses, even in the face of geometric asymmetry. We believe that analysis in future studies should use a stratified sample or regional quotas to better capture contextual diversity [59,64].

The sample analysis considering the SEM technique is as follows:

(a) Normality and reliability were analyzed based on the following parameters: (i) the Z Score test [−3 < Z < +3], which demonstrates that the sample values are on a standard distribution curve; (ii) Bartlett’s Sphericity Test, which showed a significant result at p < 0.001 for each observable variable; (iii) Mardia’s coefficient, which we used to verify the kurtosis index and did not identify any values greater than 5; (iv) Pearson’s Asymmetry Coefficient, which did not identify values far from zero; and (v) the sample mean and standard deviation indices, which are close to 1, demonstrating that the dispersion of values around the mean is relatively low.

(b) For the confirmatory factor analysis, verifying the data from the intra-block sample, the following normality and reliability parameters were verified: (i) Factor loading ≥ 0.5, which explains the variability of the construct. In the sample, two variables have significantly lower values, SSPP2 (0.025) and PSPP2 (0.211), which may indicate weaknesses in the convergent validity of the respective constructs. Despite this, it was decided to retain these items in the model because they present theoretical relevance and align with previous studies in the literature [67,72]. To mitigate this limitation, we recommend that future research reevaluate these items in larger samples or different empirical contexts to improve measurement and strengthen the model. (ii) Communality ≥ 0.5 evaluates the correlation between the variables of the construct; in the small group sample, it presented lower values. (iii) Cronbach’s alpha > 0.7, which suggests simple reliability in the exploratory sample, with an alpha of 0.866; however, in the intra-block analysis, the maintenance of values for ASPP (0.564) and PSPP (0.563) in the analysis, despite being below the conventional threshold of 0.7 [73], was considered adequate for several reasons. Firstly, this is exploratory research in a context that has still been little investigated, which allows for some flexibility in the reliability criteria, especially when the constructs are theoretically relevant [61]. In addition, the reduced number of items per construct (e.g., two or three items) may negatively impact the alpha value, as this index is sensitive to the number of items [63,74]. As a complementary alternative to Cronbach’s alpha, composite reliability was evaluated, and Cronbach’s alphas between 0.5 and 0.6 can be tolerated in the initial stages of scale development, especially in the social sciences [63,75]. The theoretical relevance of the constructs for the research objectives was also considered, reinforcing their importance even in the face of initial statistical limitations. The items were also refined through a pilot study to enhance clarity and reduce potential measurement errors. (iv) Kaiser–Meyer–Olkin (KMO) > 0.5, indicating the sample showed internal consistency in the data; we analyzed composite reliability using the parameter recommended by [67], which is > 0.7. In the total sample, the value was higher than 0.9, and in the intra-block analysis, two groups had a lower value.

(c) We identified the following for the reliability index: (i) Multicollinearity was observed in Pearson’s correlation (>0.7); in the sample, no multicollinearity values were identified, not demonstrating similar statistical behavior among the observable variables. (ii) Average Variance Extracted (AVE) = convergent validity (CV) (>0.7) and discriminant validity (DV) (less than convergent validity). The sample presents four constructs (ASPP, SSPP, PSPP, and BSPP) with AVE values below the ideal, respectively (0.392, 0.433, 0.363, and 0.477). This result can be considered acceptable in the context of applied social sciences, given an AVE of 0.4 or very close to it, and considering that the composite reliability is more significant than 0.6 for the constructs in question (0.658, 0.755, 0.594, and 0.862) [59,67]. In addition, social constructs often present a greater degree of abstraction and variability in participants’ responses, which can negatively impact the AVE [52]. Considering these issues, the theoretical relevance of the construct for understanding the phenomenon studied, and that the variables have content validity, we chose to maintain the constructs and their variables [72].

Table 2. Normality and reliability tests.

Constructs	Mean	SD *	Fator Loading	Communality	Cronbach’s Alpha	KMO *	Composite Reliability	Convergent Validity
All (EFA)					0.866	0.835	0.941	0.5
ASPP1	4.321	0.969	0.582	0.645	0.564	0.590	0.658	0.392
ASPP2	3.921	0.963	0.468	0.590
ASPP3	3.648	1.162	0.575	0.378
SSPP1	4.297	0.995	0.560	0.480	0.633	0.740	0.755	0.43
SSPP2	4.358	0.862	0.025	0.995
SSPP3	4.424	0.828	0.681	0.628
SSPP4	4.515	0.762	0.672	0.630
SPP5	4.279	0.845	0.739	0.588
PSPP1	4.303	0.768	0.679	0.665	0.563	0.578	0.594	0.36
PSPP2	3.861	1.152	0.211	0.354
PSPP3	4.194	0.903	0.597	0.595
BSPP1	4.479	0.770	0.587	0.430	0.793	0.828	0.862	0.48
BSPP2	4.309	0.935	0.715	0.574
BSPP3	3.873	1.127	0.465	0.307
BSPP4	4.721	0.569	0.470	0.295
BSPP5	3.867	1.102	0.591	0.434
BSPP6	3.945	1.100	0.657	0.534
BSPP7	4.242	0.970	0.700	0.587
SPP1	4.467	0.761	0.714	0.612	0.711	0.672	0.802	0.57
SPP2	4.576	0.606	0.648	0.675
SPP3	4.164	0.857	0.643	0.615

Notes: * SD (standard deviation), KMO (Kaiser–Meyer–Olkin). Source: Prepared by the authors.

shows the data relating to the sample according to the validation scale.

Considering the conceptual framework represented in Figure 1, which presents the influence relationships between the constructs and the CB-SEM methodology [61], the research hypotheses were tested to assess the intensity of their relationships.

Table 3. Research hypothesis.

Hypotheses	Description	Standardized Regression Weights	Intensity	Results
H1	The ASPP positively influences SSPP	0.870	high intensity	confirmed
H2	The SSPP positively influences PSPP	0.882	high intensity	confirmed
H3	The SSPP positively influences BSPP	0.392	moderate intensity	confirmed
H4	The BSPP negatively influences PSPP	0.290	low intensity	confirmed
H5	The PSPP positively influences SPP	0.814	high intensity	confirmed

Source: Prepared by the authors.

presents the results of the hypothesis tests. In all hypotheses, the p-value was less than 0.001, demonstrating the significance of the relationships.

We confirmed the hypotheses as they present significant Standardized Estimate (SE) values (p < 0.001) and are based on the Standardized Estimate (SE) parameters (SE values: less than 0.3—low intensity; between 0.3 and 0.5—moderate intensity; greater than 0.5—high intensity) [53,68]. Figure 2 presents the integrated model based on standardized regression weights that consider the correlations between the constructs and between the observable variables.

Hypotheses H1, H2, and H5 indicate a high intensity of the relationship, while hypothesis H3 indicates a moderate intensity, and hypothesis H4 indicates a low intensity, however, with a positive influence (p < 0.001).

Table 4. Model fitting parameters.

${\mathbf{x}}^2$	df	${\mathbf{x}}^2$/df	CFI	NFI	RMSEA
360.193	184	1.958	0.828	0.708	0.076

Notes: ${\mathrm{x}}^2$/df (chi-square divided by the degrees of freedom), CFI (Comparative Fit Index), NFI (Normed Fit Index), and RMSEA (Root Mean Squared Error of Approximation). Source: Prepared by the authors.

presents the model’s fit indices, indicating whether the relationships between the constructs are adequate. Column 3 is x²/df, the chi-square divided by the degrees of freedom, which is less than 5, suggesting that it is a good model [76]. The CFI, corresponding to the Comparative Fit Index, and the NFI, the Normalized Fit Index, are both less than 0.9, indicating that the model has room for improvement [77]. Although the CFI (0.828) and NFI (0.708) values are below the ideal thresholds (≥0.90), they are considered acceptable in exploratory and applied studies in the social sciences, as pointed out by [59,78], especially in moderate or small samples and with accurate data. The theoretical basis of the model and the statistical significance of the structural paths justify maintaining the proposal. The RMSEA is the root mean square error, and the model presents a good fit with a value of less than 0.08 [79]. To improve the model, we suggest that future research expand the sample, seek more excellent regional representation, develop longitudinal models, and deepen studies by exploring possible moderating variables, such as the profile of HEI respondents or the size of the institution.

We based this research on the analysis of the antecedents in SPP, their variables, and how they relate to each other, as well as the influences that may contribute to improvements in the sustainable aspects of PP. As a main contribution, we proposed and empirically tested a conceptual framework, validating an integrated model that can be applied in higher education institutions (HEIs) in Brazil as a proposal to be implemented in the institutions’ purchasing policies and later replicated in other segments of public administration.

The research hypotheses were all confirmed, indicating alignment with the theory, especially considering the need to include and expand sustainability criteria in PP, which have a significant volume and strategic role in the countries’ GDPs, as discussed in Section 2. In addition, the statistical results of this research support the hypotheses and indicate the normality and reliability of the sample. To improve the model, we suggest that future research include variables to enhance the model’s indicators, expand the sample, and increase regional representation to mitigate regional bias and increase the generalizability of the results. We also highlight the importance of exploring alternative models with different paths or grouped constructs.

The actor construct (ASPP) has a strong influence, with SE = 0.87, on the strategy construct (SSPP), indicating that the various roles of actors, such as (i) buyers increasing efficiency, reducing transaction costs, and providing transparency in resources; (ii) suppliers establishing long-term relationships with fair conditions and improving productivity; and (iii) promoters developing policies that promote more sustainable business models, strongly influence strategies in PP.

Studies indicate that in Europe, dialog and cooperation between stakeholders, including the market and the government, in its role as purchaser, facilitate the establishment of criteria and requirements for extending the product’s useful life, efficiency and/or intensity of use, efficiency, and clean cycles, promoting the circular economy [38]. The importance of competitive dialog between stakeholders is highlighted in complex public contracts within the European Union, where technical specifications are defined by legislation and the financial aspects of the project are ensured, thereby promoting fair competition and commercial confidentiality [80]. European governments develop instruments for guidance in SPP, and in the United Kingdom, purchasing standards are defined by various representations without characterizing discrimination [32].

The strategy construct (SSPP) indicates a strong influence on purposes (PSPP), with this influence being SE = 0.88, which suggests that well-positioned strategies with the support of top management, such as training, shared purchasing, promotion of local production, and supplier development, promote circular business models, quantifiable results in sustainability, and promotion of labor rights [30,38,49].

Considering that what gets measured gets managed, incorporating a strategy related to life cycle costing in SPPs enables impact management [14]. Research indicates that to assess impact and efficiency more accurately, SPP strategies should be aligned with human rights standards and international trade frameworks [36]. In the United Kingdom and Germany, strategies such as reusable trays, management systems, certifications required by the public service, and the implementation of organic foods have expanded businesses, created value chain models, and enhanced short supply chains [20,81]. In South Africa, research suggests that the government needs to improve its environmental policy strategies to promote green products and services in the context of climate change [82].

The strategy construct (SSPP) has a moderate influence on the barrier construct (BSPP), with a standardized effect size (SE) of 0.39. The barrier construct (BSPP) has a low negative impact on purposes (PSPP), with an SE of 0.29. The research sample indicates lower averages for the variables (BSPPS3), (BSPPS5), and (BSPPS6), with 3.87, 3.86, and 3.94, respectively, which indicates a perception of neither agreement nor disagreement for the barriers related to financial aspects, monitoring, and access to information; however, the variable related to training (BSPP4) presented the highest agreement rate, with an average of 4.72.

Studies in Singapore highlight that strategies related to environmental standards and energy efficiency are urgent, particularly in mitigating challenges associated with the limitation of natural resources [83]. Researchers emphasize that continuous training of public agents is crucial for enhancing technical capacity and reducing resistance to the adoption of sustainable practices [84]. Studies indicate that senior management commitment and clear political support are essential in overcoming institutional barriers. Studies in Brazil suggest that organizational culture is the primary barrier to SPP, emphasizing that cost and budget are not significant barriers; thus, this reinforces the need for cultural change management in sustainability management [8,22,85]. Authors such as [86,87] indicate that, in specific contexts, factors like institutional leadership and strategic alignment carry more weight than financial limitations. In structural equation modeling, the coefficients associated with these barriers are low or statistically insignificant [33]. According to [22,85], more mature institutions in terms of sustainable practices have already developed capabilities that mitigate the impact of operational barriers, such as limited access to information or financial resources, mainly observed in HEIs with previous experience in sustainability.

The data indicate the need for further studies on the subject, encouraging the expansion of knowledge in SPP, providing new circular business models through partnerships with suppliers, and integrating systemic solutions into the project, thereby enhancing sustainable development and achieving international development goals [35].

The purpose construct (PSPP) strongly influences the sustainability construct (SPP), with an effect size (EP) of 0.81, indicating that practical purposes help improve sustainability indices and metrics in PP through market development, integration between stakeholders, and the creation of theoretical models to assist in developing practical guidelines. Although studies indicate a solid legal framework in Brazil, it is still necessary to create a market that includes small producers and promotes more sustainable goods and services [47].

Brazil’s new procurement and contracting law, Law No. 14,133/2021, includes guidelines for sustainability in public administration, but there are regulatory nuances that limit the applicability of models in SPP. Historical judgment practices centered on the lowest price are a cultural and technical barrier, as evidenced by the resistance of managers and control bodies to adopt qualitative or life cycle criteria due to concerns about legal challenges and the difficulty of measuring sustainable benefits [22].

HEIs have greater administrative and technical autonomy, which facilitates the development of innovative initiatives in sustainable procurement, such as preparing terms of reference with technical environmental criteria. Other institutions in the public sphere may be more rigid, with limited technical capacity, less autonomy, and stricter legal control, thus hindering the implementation of more sustainable models in public procurement [22].

This research indicates that analyzing antecedents in SPP, along with their influences and integration, can lead to an increase in sustainability indices in PP by incorporating criteria outlined in the conceptual framework and the proposed model for purchasing policies in HEIs. The hypotheses that have the most significant influence, such as H1, H2, and H5, should be prioritized, and those related to barriers should be more thoroughly evaluated in light of the specific needs of each institution.

Higher education institutions can benefit from adapting their purchasing policies and organizational processes to the data from the proposed model and the considerations of this research, thereby contributing to improvements in sustainability indices in public procurement. Examples include encouraging dialog between the various stakeholders as a way of institutional improvements and encouraging the promotion of public policies focused on SPP; ongoing training; creation of specialized SPP centers; strengthening collaborative networks; senior management committed to sustainability; procedure manuals with more sustainable criteria; cultural change management; and SPP monitoring and indicator systems, among many others that were analyzed in this research.

Although the proposed model has been validated using data from Brazilian higher education institutions (HEIs), we acknowledge that its applicability is limited to other contexts. Even in Brazil, other public institutions have different institutional structures, regulatory frameworks, and cultural aspects. In Brazil, there is still a strong predominance of criteria centered on the lowest price. At the same time, countries in the European Union have more specific guidelines for SPP, such as directives 2014/24/EU. Considering the institutional, regulatory, and cultural differences, adapting the model is necessary for its application in other segments of Brazil and other countries.

5. Conclusions

This research aimed to analyze the antecedents in SPP and their influences and to develop proposals for improvements that can increase the sustainability index in the acquisition of products and services by HEIs. The results offered the following theoretical contributions and empirical evidence: (i) development and validation of antecedent constructs in SPP; (ii) evidence of causal relationships between the constructs; (iii) empirical testing of a theoretical framework and validation of an integrated model in SPP; (iv) identification of antecedents in SPP, comprising actors, strategies, and purposes, that significantly influence sustainability improvements in PP, demonstrating their strategic importance; and (v) recognition that barriers are an antecedent in SPP and negatively influence the purposes in SPP, demonstrating the importance of knowledge on the subject to mitigate their adverse effects.

This research provides valuable insights for managers, policymakers, and researchers in SPP. It emphasizes the need to assess the characteristics of the main antecedents in SPP to understand the relationships between the constructs and their impacts on sustainability. This research highlights certain practices of actors, such as buyers seeking cost reduction, transparency in the process, and competitive dialog between suppliers and public institutions, as well as promoters of public policies who provide improvements in human rights, minority inclusion, and gender equality, which influence more sustainable strategies. Strategies related to supporting senior management, such as training and management systems, as well as criteria that promote a circular economy, including environmental compliance certificates, reuse, and recycling, promote local and organic production. Technological solutions integrated into the project mitigate possible SPP barriers and provide more sustainable purposes in acquisitions. Obstacles related to culture, awareness, and knowledge were the most evident in the survey of the HEIs researched, and this negatively influenced more sustainable purposes. Financial and monitoring aspects were not highlighted in the HEIs analyzed. Developing the market and integrating different actors and theoretical models were identified in the survey as necessary for improving sustainability indices in public procurement.

As a limitation, this study theoretically analyzes SPP in a generalized way but empirically tests only one group, Brazilian HEIs. By considering only one group, this research restricts the applicability of the results to other organizational contexts, and caution is needed when analyzing models outside the universe of HEIs in Brazil. Another limitation of this study is the snowball sampling technique, as it may not reach specific groups and can introduce bias by selecting similar individuals, which could compromise the representativeness of the sample and potentially lead to more homogeneous perceptions. However, this effect may have been mitigated by the inclusion of different institutional and regional profiles.

Future research could explore other segments of public administration, analyze differences between sustainable purchases in the public and private sectors, conduct comparative studies in SPP between developed and developing countries, adapt the model, considering the existence of other constructs and other variables, and seek more representative samples that can impact sustainability in public purchases.