Investigation of Product–Service System Components as Control Points for Value Creation and Development Process

: Since the early 2000s, product–service systems (PSS) have become a research concern because the beneﬁts provided cover many aspects. PSS is divided into three types, namely, Type 1: product-oriented, Type 2: use-oriented, and Type 3: result-oriented. PSS is a system comprising different components. As a system compiler, the components are the starting point for the value-creation process and continue to impact the PSS’s life cycle. However, elaboration of PSS components in previous studies has lacked. This situation indicates an urgent need to investigate PSS components and, thus, our evaluations of the value creation and the developmental processes of PSS seek to be broad and divergent. The investigation that forms the purpose of this article includes an elaboration of the PSS components, a calculation of the PSS components’ importance levels, statistical testing of the differences in importance levels due to PSS type, correlation testing between components, and a determination of the PSS components concerning the sustainability aspect based on the perspective of customers. The investigation began with the development of a questionnaire and a reliability–validity test. In addition, we identify the PSS components, test the difference in importance level using the Mann–Whitney test, and survey customers to determine the sustainability-related components. This article’s ﬁndings can be used to specify the critical point for value creation and PSS development. The elaborated PSS components are products, services, actors, stakeholder relationships, and technology. The difference in importance level indicates that PSS Type 2 customers perceive a distinction in the importance of technology. The essential components of each type of PSS are distinct, necessitating the use of different development strategies, including for sustainability aspects.


Introduction
Pressure from the competition and rapid technological changes have forced the manufacturing industry to regard service as an added value and product differentiator [1]. The trend of service involvement in value creation in the manufacturing industry has given rise to the term "servitization". Servitization increasingly requires manufacturers to transition from product to product and service integration [2]. Service has shown its contribution to value creation on a non-price basis [3], increasing a firm's economic value [4] and increasing customer loyalty [5]. Based on these benefits, PSS is growing as a manifestation of the integration of products and services [6]. According to the typology, there are three types of PSS, namely Type 1: product-oriented, Type 2: use-oriented, and Type 3: result-oriented [7]. In the product-oriented type, the proportion of products is more significant than the service. In the result-oriented type, the service is prominent. While in the use-oriented type, the balance of products and services is flexible. Although each has a different characteristic, the three types of PSS can form a strategic innovation for manufacturing [8]. PSS is an integrated system of products, services, support networks, and infrastructure designed to meet customer needs, increase competitiveness, and impose a lower environmental impact than traditional business models [9]. The PSS business model increases collaboration The findings of this research will enhance the use of PSS components as control points for value creation and the PSS development process.

Materials and Methods
Several research steps are depicted in Figure 1. Step 1 Step 2 Step 3 Step 4  Step 1 was a questionnaire design survey for the PSS component investigation. A literature review on PSS was used to identify those critical aspects of value creation and value delivery that satisfy the component definition. Numerous previous studies have concurred that PSS consists of products and services that are intentionally designed for specific values [15,29,[50][51][52][53][54]. In addition to products and services, the success of PSS also depends on the actors in charge of delivering value to customers [29]. There are two groups of actors: external and internal. Collaboration between external and internal actors significantly affects the PSS development process [52]. Complex PSS currently necessitates good relationships among actors. These relationships are critical to value creation and delivery [51]. The relationship is multi-actor and includes other stakeholders related to the primary resources and strategic factors [53]. The Industrial Revolution 4.0 has also influenced the development of PSS so that technology becomes one of the critical aspects of value creation and delivery [55]. This article elaborates on PSS components based on a literature review, and the definition of components includes products, services, actors, stakeholder relationships, and technology. The five elements were then assembled into a questionnaire.
Step 2 of the research was data collection through a customer survey. The purpose of the survey was to explore ideas and evaluate the importance levels of the PSS components discovered in the literature search. Respondents in this survey were Indonesians who had experience using PSS Type 1, Type 2, or Type 3. Respondents had similarities in culture, government policies, and habits in meeting daily needs. Thus, the sample was selected at random from a vast population. The sample size determination follows confidence  Step 1 was a questionnaire design survey for the PSS component investigation. A literature review on PSS was used to identify those critical aspects of value creation and value delivery that satisfy the component definition. Numerous previous studies have concurred that PSS consists of products and services that are intentionally designed for specific values [15,29,[50][51][52][53][54]. In addition to products and services, the success of PSS also depends on the actors in charge of delivering value to customers [29]. There are two groups of actors: external and internal. Collaboration between external and internal actors significantly affects the PSS development process [52]. Complex PSS currently necessitates good relationships among actors. These relationships are critical to value creation and delivery [51]. The relationship is multi-actor and includes other stakeholders related to the primary resources and strategic factors [53]. The Industrial Revolution 4.0 has also influenced the development of PSS so that technology becomes one of the critical aspects of value creation and delivery [55]. This article elaborates on PSS components based on a literature review, and the definition of components includes products, services, actors, stakeholder relationships, and technology. The five elements were then assembled into a questionnaire.
Step 2 of the research was data collection through a customer survey. The purpose of the survey was to explore ideas and evaluate the importance levels of the PSS components discovered in the literature search. Respondents in this survey were Indonesians who had experience using PSS Type 1, Type 2, or Type 3. Respondents had similarities in culture, government policies, and habits in meeting daily needs. Thus, the sample was selected at random from a vast population. The sample size determination follows confidence interval limits, in which the researcher believes the error will not exceed the error margin [56]. The Cochran formula, shown in Equation (1), determines the sample size for populations with numerous members [57].
where: n is a sample size Z α is a standardized normal distribution value for specific alpha p is the proportion of people who have used PSS q is the proportion of people who have not used PSS e is an error margin. There were validation questions in the questionnaire used to filter the data so that the processed data came only from respondents who had experience with specific PSS. The value of p was calculated by dividing the number of respondents who had used a particular type of PSS by the initial observation of 30 respondents. The sample size must be logically determined to strike a good balance between effort, time, cost, and estimates of population parameters [58]. The researcher was 90% confident that the difference between the sample statistics and the population parameter was less than 0.1. Thus, the value of alpha and margin error is 10%. Table 1 presents the determination of sample size for each type of PSS. After determining the sampling method and the sample size, a pre-sample of 60 respondents was used to test the questionnaire's reliability and validity. Previous studies have emphasized the importance of reliability and validity tests because they are used as criteria for the quality of the questionnaire [59]. A reliability test ensures consistent results if the questionnaire is given to a respondent at different times or to several respondents simultaneously [60]. Cronbach's Alpha is a coefficient often used to indicate reliability, which is divided into several categories, as in Table 2 [61]. The result of the reliability test in this research is presented in Table 3. showed the quality of the questionnaire in measuring the importance of the PSS components identified in previous studies. Suppose the validity test results obtained invalid results. In that case, the PSS component as a question variable in the questionnaire must be deleted because it is significantly irrelevant to the intended PSS. The PSS component was considered valid if the corrected item-total correlation value was greater than the r-table value of 0.2542. Table 4 shows the results of the validity test. The reliability and validity test results indicate that the questionnaire and the data obtained could be accounted for in answering the objectives of this study. The investigation of the PSS component in this article consisted of identifying the PSS component by elaborating on previous studies and surveys; testing different populations for the PSS components' importance level in each type; calculating the PSS components' importance level; analyzing the correlation between the PSS components, and calculating the percentage of the PSS component associated with sustainability.
Exploring previous studies, recognizing the PSS part's role in influencing value, and ensuring its suitability in terms of the definition of a component were the steps in identifying the PSS component. Efforts to identify PSS components considered the type of PSS. The differences in these characters are described in Table 5 [7]. The firm sells the product and provides the necessary services for its use.
The firm provides guidance or consultation on how to use or the most effective way to use the products it sells.
2 Type 2: Use-Oriented Ownership of the product rests with the firm, not the customer. The firm is responsible for carrying out maintenance, repair, and control. The customer, also known as the lessee, pays a regular fee for using the product. However, the leaser has unrestricted access or use rights to the leased product. The customer does not have unlimited access or use rights to the product. Meanwhile, product ownership and responsibility for maintenance, repair, and control are still with the firm.
Multiple partners are gathered in one location, and the product is simultaneously utilized.
The customer no longer purchases the product but instead pays a fee based on the product's output and level of use.

Type 3: Result-Oriented
The firm's tasks are delegated to third parties through outsourcing contracts, but the quality of the work is still monitored using performance indicators.
The firm conveys results, which can be in the form of products or services, to clients.
After knowing the classification of PSS and its characteristics, an identification of PSS components was carried out. Based on the research of previous studies, Table 6 shows key aspects of value creation fitting the definition of components. Technology [15,50,[53][54][55]62,[67][68][69][70][71][72] In the interim, various responses were obtained from customer surveys. Using an affinity diagram, some answers were categorized into the PSS component extracted from prior studies, while others were irrelevant to the definition of the component. Table 7 displays the results of customer identification based on a survey.  Step 3 of the research was data processing, including an examination of PSS component importance levels and the relationships between different PSS components in terms of sustainability. After elaborating on the PSS components, the investigation continued with a population difference test of the PSS components' importance levels for each type. The results can be used to consider specific treatment needs for each component in planning value creation and PSS development. The test was carried out by using the Mann-Whitney test. The Mann-Whitney test is used to examine the difference between two independent populations through the median without knowing the distribution of the two populations [73]. In cases with unequal sample sizes, the error probability cannot be well controlled by either the Student's t-test or the Mann-Whitney test; however, even in that case, the Mann-Whitney test is still better than the Student's t-test [74,75]. The hypotheses built for the Mann-Whitney test are presented in Table 8.
Assess whether PSS Types 1 and 2 have different levels of importance for the product as components. 2 Assess whether PSS Types 1 and 3 have different levels of importance for the product as components. 3 Assess whether PSS Types 2 and 3 have different levels of importance for the product as components.
Assess whether PSS Types 1 and 2 have different levels of importance for the actor as components. 8 Assess whether PSS Types 1 and 3 have different levels of importance for the actor as components.

9
Hypothesis 9 H 0 : Assess whether PSS Types 2 and 3 have different levels of importance for the actor as components.

10
Hypothesis 10 Assess whether PSS Types 1 and 2 have different levels of importance for the stakeholder relationship as components.

11
Hypothesis 11 Assess whether PSS Types 1 and 3 have different levels of importance for the stakeholder relationship as components.

12
Hypothesis 12 Furthermore, calculating the PSS components' importance levels was analogous to calculating the mean importance level of attributes in the SERVQUAL case [76]. Table 9 displays the average importance of PSS components for Types 1, 2, and 3. The importance level measurement used a scale of 4. The investigation continued into the correlation analysis between components. PSS is a system composed of synergistic components that contribute to overall value creation. Therefore, studying the interaction between components is vital for an examination of value creation or PSS development. Several coefficients can be used to show the relationship between variables, such as Kendall's τ, the Ghini measure, Blomqvist's β, Spearman's ρ, and Pearson's correlation [77]. Spearman's ρ and Pearson's correlation are two coefficients commonly used in statistical testing [78]. Spearman's ρ is considered a regular Pearson's correlation regarding the proportion of variability taken into account [79]. Pearson's Sustainability 2022, 14, 16216 9 of 23 correlation explains the relationship between two variables through a linear function, while Spearman's ρ does this through a monotonic function [80]. By using the monotonic function, Spearman's ρ does not need to pay attention to the distribution of the data and is suitable for use on a Likert scale with a value level [81]. Therefore, Spearman's ρ was used in this study to analyze the relationship between PSS components in each type. The last investigation into PSS components was undertaken to determine the relationship between PSS components in terms of sustainability, based on the voice of the customer. A comparative analysis was carried out between the types of PSS based on the data obtained. Thus, firms concentrate on the components that contribute to the value creation and development of PSS in terms of sustainability for PSS Types 1, 2, and 3.
Step 4 of the research was the result and conclusion. At this stage, the research results are discussed and summarized to contribute to the current development within the PSS industry and its research and to elaborate future research opportunities.

Results
There are three types of PSS with eight characteristics that are influenced by the dominance of the PSS components that constitute them. Referring to the definition of components, the results of the identification of PSS components from previous studies are presented in Table 6. Based on the description of PSS, many previous studies agree that products and services are components of PSS [9,27,82]. Product and service integration prioritizes the value creation process and value delivery over resources [83]. In addition, actors as subjects in value creation and value delivery have begun to be research topics, with related research including the design of an actor-network map, to map tasks and enhance the roles of actors [63,69], and the investigation and development of collaborations between actors to support their functions both internally and externally [52,62]. Previous studies have shown an appreciation for the significance of collaboration between actors and stakeholder relationships. Stakeholder relationships are needed in value creation between actors [6]. Customer surveys have also supported the importance of stakeholder relationships in value creation and delivery for PSS Types 1, 2, and 3. As shown in Table 7, customers stated that collaboration, experience, and influence between stakeholders affected the value creation and value delivery processes of PSS. Along with Industrial Revolution 4.0, the critical role of technology in servitization has been consistently increasing [84], thus affecting the evolution of PSS [55]. Based on the previous studies' exploration, the elaborated PSS components were product, service, actor, stakeholder relationship, and technology. Referring to the definition of components, these five components were designed intentionally to support the value creation and delivery in various patterns and standards. If there was a failure in the product, service, actor, stakeholder relationship, or technology, the PSS offered to customers failed because it did not match the set value.
The identified PSS components were in line with the results of the customer survey through open-ended questions. Most of the respondents provided diverse responses, yet it turned out that the reactions remained related to the PSS component attributes found in the previous study. The results of the polarization of the answers are presented in Table 7. Meanwhile, several respondents answered critical aspects of value creation that needed to be more relevant to the definition of components. In PSS Type 1, many customers conveyed ideas related to the product, such as product quality. This was following the characteristic of PSS Type 1. PSS Type 1 places a heavier emphasis on the product aspect of product and service integration [7]. Meanwhile, the ideas customers conveyed the least were related to technology and included information systems and social media. In PSS Type 1, technology supports PSS, as, for example, in knowledge management tools [85]. PSS Type 2 was distinct in this regard. In Table 7, it was evident that customer ideas were diverse and relatively dispersed across the five PSS components. As an implication, customers perceive equality in terms of the dominance of each component over the other. This follows the requirements of PSS Type 2, which has four distinct characteristics. These characteristics are displayed in Table 5. In PSS Type 3, customers considered the flexibility of all components to be necessary for the value creation and value delivery processes. This follows the characteristics of PSS Type 3, requiring flexibility to gain diverse customer loyalty.

The Components' Importance Level Difference Test between PSS Types
An investigation of components' importance level differences between PSS types was conducted using the Mann-Whitney test. The decision in the Mann-Whitney test was drawn by comparing the p-value and alpha of 5%. The null hypothesis was rejected if the p-value was less than the alpha of 5%. Table 10 shows the result of the Mann-Whitney test, which was based on the hypothesis shown in Table 8. The two-population test results shown in Table 10 were utilized for the value creation evaluation and PSS development plan. If the test results show no difference between the two populations being tested, customers have the same view of the importance level of specific PSS components in all types of PSS. Thus, the firms do not need to give special treatment to the PSS component when preparing the value creation evaluation and development plan, even though it is a different type of PSS. The results of the Mann-Whitney test displayed in Table 10 show differences in the importance level of the technology component for PSS Type 1 versus PSS Type 2 and PSS Type 2 versus PSS Type 3. Furthermore, there was no difference in the importance level of the technology component between PSS Type 1 and PSS Type 3. Customers perceived the critical role of technology in PSS Type 2. Referring to Table 5, there are four characteristics of PSS Type 2 that require technological assistance in accelerating the value creation and value delivery of PSS. Regarding leased product maintenance, technology can act as a communication channel to facilitate and expedite access, as a knowledge management manager, and as a maintenance, repair, and operation tool. As a control point for value creation and the development of PSS Type 2, the technology needed special attention because customers gave different levels of importance to it than they did PSS Type 1 and PSS Type 3.

The Components' Importance Level
Components are an essential part of PSS for value creation and delivery processes that are tailored to the type of PSS. For example, in PSS Type 1: product-oriented, the product as a component is more prominent than other components. Therefore, it is necessary to investigate the importance of the PSS component in each type based on the customer's perspective. Figure 2 shows how the significance of the PSS components was judged from the customer's point of view for the three types of PSS. will interact with other components and create a particular value. Technology is always in third place for every PSS type. However, the importance of technology in PSS Type 2 differed significantly from that in PSS Type 1 and PSS Type 3. This was supported by the results of the two population tests presented in Table 10. Considering the broad and diverse scope of PSS Type 2, technology plays a vital role in the value creation and delivery processes in PSS Type 2. As in Figure 2b, the service component was in second place and the product component was in third place. As an implication, the wide variety of PSS Type 2 components requires firms to be responsive and adaptive to changes in the business environment, such as changes in market trends and customer tastes. Technology and service are components that assist firms in responding to these demands. Technology improves process efficiency rapidly so that customers become satisfied. Meanwhile, service provides attractiveness through unique and creative offers so that customers feel fulfilled.
On the other hand, other components will continue to work to support the value creation of PSS.

Correlation between PSS Components
Decision-making in the Spearman correlation test is conducted by comparing the pvalue with 5% alpha. If the p-value is less than alpha, the null hypothesis is rejected. In general, the hypothesis tested on Spearman's is H0: ρ 0, which means there is no correlation between the two PSS components Ha: ρ 0, which means there is a correlation between the two PSS components Table 11 presents the results of the Spearman correlation test.   Table 9. Figure 2a demonstrates that the product is the most critical component of PSS Type 1. As an implication, customers of PSS Type 1 are focused on the product, and the product becomes the driver of value creation and value delivery for consumers. Furthermore, Table 7 shows that customers focus on a product's quality, warranty, design, and other features that are representative of the voice of the customer when regarding the product's importance. After the product, PSS Type 1 also considers service to be a significant component. The service is considered capable of attracting customers even though the product is still the main focus of PSS Type 1.
In contrast to PSS Type 3, Figure 2c demonstrates that the essential component is service. In the result-oriented type, most firms offer creative and attractive service designs. Meanwhile, the product is a side offering that can support the service process. In the use-oriented type, most firms demand rapid, widespread, and enormous data handling for customer service, so technology plays a significant role. As an implication, firms need to focus not only on service and product innovation but also on the preparation of technology to help with service delivery in PSS Type 2. In value creation, each component will interact with other components and create a particular value. Technology is always in third place for every PSS type. However, the importance of technology in PSS Type 2 differed significantly from that in PSS Type 1 and PSS Type 3. This was supported by the results of the two population tests presented in Table 10. Considering the broad and diverse scope of PSS Type 2, technology plays a vital role in the value creation and delivery processes in PSS Type 2. As in Figure 2b, the service component was in second place and the product component was in third place. As an implication, the wide variety of PSS Type 2 components requires firms to be responsive and adaptive to changes in the business environment, such as changes in market trends and customer tastes. Technology and service are components that assist firms in responding to these demands. Technology improves process efficiency rapidly so that customers become satisfied. Meanwhile, service provides attractiveness through unique and creative offers so that customers feel fulfilled. On the other hand, other components will continue to work to support the value creation of PSS.

Correlation between PSS Components
Decision-making in the Spearman correlation test is conducted by comparing the p-value with 5% alpha. If the p-value is less than alpha, the null hypothesis is rejected. In general, the hypothesis tested on Spearman's is H 0 : ρ = 0, which means there is no correlation between the two PSS components.
H a : ρ = 0, which means there is a correlation between the two PSS components. Table 11 presents the results of the Spearman correlation test.  As an implication, the information obtained from correlation is for component treatment. If there is a significant relationship between components, treating specific components will affect other components. Based on Table 11, most of the PSS components were related. In PSS Type 2, the obtained information showed that the stakeholder relationship component and the product did not have a significant relationship, and the same was true of the stakeholder relationship and service components. This indicates that the variability of the importance of products and services is not linearly related to the variability of stakeholder relationships. Changes in stakeholder relationships will not affect changes in products and services or vice versa. As an implication, firms can engineer products and services without paying attention to the customer's view of the stakeholder relationship. Changes in products and services are more related to technological changes. The p-value for product and technology and service and technology was smaller than alpha 5%. This result supports the results of the Mann-Whitney test, which shows that customers felt the role of technology was more critical in PSS Type 2 than in Types 1 and 3. The examples of business fields in PSS Type 2 are cloud drives, equipment rental, Gojek, Grab, Uber, Market Place, and Copier Producer. This industry is directly tied to the role of technology. Thus, the products and services offered to customers will also be impacted. Technology also has a significant correlation with stakeholder relationships in PSS Type 3. As a result, firms prioritizing the building of relationships with stakeholders also need to emphasize the development of technology. The PSS Type 3 offered to customers is focused on results, which good relationships with stakeholders will facilitate. Technology supports the building of stakeholder relationships through the provision of advanced facilities. In addition, a significant correlation exists between stakeholder relationships and actors in PSS Type 1. This is the background of the need for collaboration between actors in value creation and value delivery related to product and service integration and supported by technology.

The Sustainability-Related Components
Based on Figure 3a, the dominant component related to sustainability in PSS Type 1 was the product component. This fits with the characteristics of PSS Type 1, which focuses on products in the integration of products and services. As a result, products will play a significant role in achieving sustainability. Implementing product life cycle management (PLCM) improves the products' function in terms of sustainability. PLCM enables the creation of a closed-loop supply chain through the product design process. When a product reaches the end of its useful life, a closed-loop supply chain allows for reuse, remanufacturing, and recycling. Thus, a circular economy, sustainable materials selection, and green product design and production techniques achieve sustainability. Meanwhile, the proportion of products and services is potentially balanced in PSS Type 2, so that service can play an essential role in achieving sustainability. This can be seen in Figure 3b. Service innovation provides fewer products and the concept of dematerialization. Product and service integration offers a new alternative for customer consumption materials away from tangible products and towards intangible products. Thus, there is business sustainability for the firm, which can then focus on producing products to keep the market going while finding ways to help customers keep their business. In addition, the service offering influences customers to accept remanufactured products more readily. Thus, product and service integration creates closed-loop resource flows [6]. Operationally, product and service integration will require technology as a supporting tool that contributes to the achievement of sustainability. These achievements can be seen in the efficiency of the processes that can be carried out by technology. This is in line with the survey results shown in Figure 3b. Technology was in second place after service regarding its relationship to sustainability. Figure 3c shows that the stakeholder relationship is most related to sustainability. In PSS Type 3, or result-oriented PSS, the PSS often relates to customers or other stakeholders. Thus, achieving the sustainability goal will depend on how much each stakeholder knows about green processes, green products, green services, and green partners. This is supported by the survey results shown in Figure 3c. The stakeholder relationship component had a percentage that was not very different from the product, service, and actor components. Customers are provided products and services, whereas actors are the subjects of PSS delivery to customers.

Discussion
As the system is a collection of interacting entities, it is necessary to clarify the PSS components to understand the system thoroughly [86]. Components conforming to the designer's expectations can contribute to the function of the PSS under the purpose of its creation. These functions relate to value creation and value delivery. Thus, PSS components are utilized as the control point for value creation, value delivery, and PSS development. The value creation process begins with the development of components that make up the PSS. Each component has a specific function and role in supporting a PSS. Each component synergizes with other components to form a PSS with particular values throughout its life cycle. The PSS component will affect value creation and value delivery. Based on the excavation of previous research and customer surveys, the PSS components elaborated are product, service, actor, stakeholder relationship, and technology.

Product
The product is one of the physical aspects of PSS offered to customers. Customers can capture the existence of the product through the five senses. The critical elements of the physical product definition are geometry, material specifications, and process plans [87]. Products contribute to value creation through certain functions related to these critical elements. The product underwent a role change in PSS and is no longer the primary value provider [88]. However, products as tangible commodities are still used to meet user needs [89]. Therefore, the product can be used as a control point for value creation and PSS development related to reliability, design, and conformity.
Service Service is part of an industry with elements of action, performance, effort, or process that must be delivered to customers. According to the new concept, service is seen as an activity involving both the firm and the client with value creation deriving from the process [88]. Four service characteristics can be compared with the characteristics of the

Discussion
As the system is a collection of interacting entities, it is necessary to clarify the PSS components to understand the system thoroughly [86]. Components conforming to the designer's expectations can contribute to the function of the PSS under the purpose of its creation. These functions relate to value creation and value delivery. Thus, PSS components are utilized as the control point for value creation, value delivery, and PSS development. The value creation process begins with the development of components that make up the PSS. Each component has a specific function and role in supporting a PSS. Each component synergizes with other components to form a PSS with particular values throughout its life cycle. The PSS component will affect value creation and value delivery. Based on the excavation of previous research and customer surveys, the PSS components elaborated are product, service, actor, stakeholder relationship, and technology.

Product
The product is one of the physical aspects of PSS offered to customers. Customers can capture the existence of the product through the five senses. The critical elements of the physical product definition are geometry, material specifications, and process plans [87]. Products contribute to value creation through certain functions related to these critical elements. The product underwent a role change in PSS and is no longer the primary value provider [88]. However, products as tangible commodities are still used to meet user needs [89]. Therefore, the product can be used as a control point for value creation and PSS development related to reliability, design, and conformity.
Service Service is part of an industry with elements of action, performance, effort, or process that must be delivered to customers. According to the new concept, service is seen as an activity involving both the firm and the client with value creation deriving from the process [88]. Four service characteristics can be compared with the characteristics of the product component: intangibility, heterogeneity, inseparability, and perishability [90,91]. Intangibility means that a service is invisible and has no tactile quality, but its existence can be felt through emotional factors. Heterogeneity means that service cannot be standardized or made to feel personal. The different customer experiences affect how service is given. Inseparability implies that services are produced and consumed simultaneously, thus requiring customer involvement. Perishability means that the service cannot be preproduced or stored but has a particular period in which it satisfies customers, which is affected by market trends. Through these four characteristics, services contribute to the value creation of PSS. Thus, services can be used as control points for value creation and the PSS development process by paying attention to the indicators derived from the four service characters. Intangibility indicators can be used concerning customer emotions. Service can be defined based on the actions performed on the customer or the nature of the ownership granted to the customer [92]. Through these actions or ownership, a response will appear in customer emotions. Customers experience emotion because they perceive a value. The emotion of satisfaction is one such example. Excellent service delivery provides satisfaction [93] because there is value as an intermediary between excellent service and satisfaction [94]. In heterogeneity, factors relating to the adequacy of customer expectations can be utilized to determine the customer's tolerance zone [95]. In inseparability, factors relating to consumer participation and intimacy can be used to facilitate the establishment of relationships with reciprocal advantages. Perishability can be utilized as a service innovation indicator. In the ecosystem, services can be categorized based on their supporting, regulating, provisioning, and cultural roles [96]. Service contributes to the value creation of PSS, so service is therefore one of the components of PSS.
Actor PSS delivery to clients involves value-creation activities with specific functions. For these activities, the actor has a critical role as the subject. A life-cycle-oriented PSS involves actors in the design process [54]. Failures that occur due to actor errors affect the value conveyed to customers or the other actors in the value chain. Actors who are also stakeholders have contributed to efforts to build stakeholder engagement. Therefore, the actor's competence needs to be considered. For example, digital competence is required when evaluating and developing smart PSS. Actors have a critical role in value creation and value delivery from PSS, so the actor is one of the PSS components that can be used as a control point for value creation and development of PSS because it supports cross-domain knowledge sharing [97].

Stakeholder relationship
Stakeholder theories discuss how stakeholders impact product development and are related to market information for product development [65]. This stakeholder engagement can be reflected in the broad and close stakeholder relationship. The idea of PSS itself shows how meaningful the relationships are between stakeholders. PSS is the ultimate customer-firm relationship with mutual benefits regarding costs, resources, performance, and innovation ideas [98]. The stakeholder relationship is indispensable in realizing stakeholder engagement, which can provide several advantages such as credibility, the anticipation of controversy, the assurance of transparency and accountability, increasing relevance, the improvement of quality, and enriched feedback [99]. Stakeholder integration in the design and development of PSS involves customers, firms, and value chain actors [64]. PSS is a blend of products and services supported by network actors and can be part of a particular business model or innovation strategy [51]. A strong actor-network can be seen from the abilities of each actor and the number of actors that can help the intended value-creation process. In the meantime, the relationship reflects how well stakeholders partner with each other. This is one of the points in evaluating the performance of the product and service mix [66]. The stakeholder relationship is designed and built to support the value creation of PSS.

Technology
At the moment, firms are required to offer PSS and to understand customer habits throughout the PSS life cycle [100]. In this case, technology supports the process. Technologies such as the Internet of Things (IoT), cloud computing (CC), and big data analytics (BDA) can increase the adoption of innovative services in manufacturing [68], accelerate the servitization process through value creation, and improve customer relationships as part of Industrial Revolution 4.0 [67,71]. In strategic interests, firms utilize remote monitoring technology for service integration [101]. Technology also improves service functions to satisfy customer desires and expectations [70]. The role of technology is also increasingly visible in PSS related to value co-creation and the achievement of sustainability [102]. Technology changes the way one creates value by embedding technology in the product, acting as a medium and tool for the generation of value-added e-services as a solution package [103]. Technology can develop PSS into smart PSS, a trending research concern [104]. Another role of technology in the value delivery process from PSS is as a communication channel, product administration, or customization offering [105]. Based on the critical role of current and future technology for PSS, technology can be considered one of the components of PSS, one which is used as a control point for value creation and PSS development. These control points can be related to technical problems, critical evaluation or performance, or problem-oriented usage [106]. Tables 6 and 7 are the basis for elaborating on the five PSS components. This is slightly different from other references, which state that the PSS component consists of products, services, supporting networks, and infrastructure [9,88]. The supporting network is related to knowledge, capacity, a collaborative network, and resources. Meanwhile, supporting infrastructure provides a supportive network that includes production plants, service agents, basic facilities, and ICT. However, the scope of supporting networks and infrastructure is divergent. Narrowing the scope of supporting networks and infrastructure facilitates the identification of the aspects influencing the PSS value. In addition, actors, stakeholder relationships, and technology have been frequently discussed in previous studies. These are all critical components of PSS's value creation and delivery process. These three things are compatible with the definition of components and are in line with the coverage of the supporting network and infrastructure mentioned above. The PSS component must be specific and critical as a control point for value creation and PSS development. In addition, identifying other components of the supporting network and infrastructure can be an exciting topic for future research, considering that PSS is still growing following industry developments and customer tastes.
The elaborated PSS components in this article can be utilized by industry and researchers. Fulfilling customer requirements starts with the five components of the PSS, which are carried out during the PSS design stage and will continue to be carried out simultaneously at the next step. The five components of PSS will remain influential throughout a PSS's life cycle. A firm can control and design the expected PSS by knowing how these five components work. Evaluating value creation, value delivery, and PSS development can be focused on particular components. These priorities should consider the customer's viewpoint so that the firm's decision will effectively meet customer requirements. In addition, the correlation between components also needs to be considered because improving a component can be pervasive and simultaneous. This article discusses the priorities and correlations between PSS components in PSS Types 1, 2, and 3, which can be used as references in the evaluation process of value creation and PSS development. The results of the Mann-Whitney test show that firms need to maximize the role of technology in the processes of value creation and value delivery in PSS Type 2. Technology plays many roles in PSS, such as acting as a communication media between stakeholders, production tools, information systems, knowledge management tools, and other roles. Customers view technology's role as more significant in PSS Type 2 than in PSS Types 1 and 3. In PSS Type 2, the dominance of products or services can be proportioned so that other components are required to bolster the value creation and delivery processes. However, additional research is necessary to determine the type of technology that most affects value creation and delivery processes. In addition, the priority of component development from the perspective of an MCDM-based firm is also an exciting and valuable research topic. PSS research is still growing, as a result of the many benefits provided by PSS on aspects of customers, firms, government, society, and the environment. Therefore, PSS is closely related to the issue of sustainability. PSS has the potential to reduce the number of products by introducing alternative product usage scenarios [107,108], and firms become more responsible for product service in the case of closed material cycles [6,107]. Firms are encouraged to perform material recovery when the product enters the end-of-life phase so that less waste is burned or stockpiled and so that they support a circular economy [6,16,27,89,107]; PSS can change the development of technical dematerialization because the customer only pays for the service or function on offer [107]. This article has presented the PSS components that are related to achieving sustainability based on customers' perspectives as users of PSS Types 1, 2, and 3. Based on the information in this article, firms can select PSS components to be developed to contribute more to the achievement of sustainability. In the future, research can be undertaken on the link between the PSS components and the achievement of sustainability. Suppose the development of PSS components is conducted through collaboration, in that case, a multi-echelon mathematical model for the supply chain can be used for future research, one that optimizes component development by increasing cooperation in stages [109]. In addition, grey flexible linear programming can be used to cope with uncertain parameters in the development of PSS components [110].

Conclusions
This article summarizes the findings of an investigation into PSS components utilized as convergent control points for value creation and PSS development. The investigation consisted of elaborating on the PSS component from previous research and surveys of customers, testing the difference in importance of the components, calculating the significance of the PSS components, and determining the PSS components related to sustainability based on customers' perspectives. Firms and researchers can utilize the results of this article to determine critical points in the evaluation and development of PSS because the PSS component is one constituent of PSS, one that plays a role in value creation and delivery. This article is part of initial research on PSS development that provides directions for an understanding of the characteristics of PSS constituents. The directions derived from this research findings are a research contribution. The findings that researchers and firms can utilize are as follows:

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The elaborated PSS component can explain, based on previous research and customer perspectives, the way that PSS constituents play an essential role in the value-creation process. This means that attention in the development of PSS can be focused on developing and managing these components effectively and efficiently.

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The importance of the PSS components presented in Table 9 and Figure 2 can be utilized to consider which component of the PSS development to start with. The level of importance was calculated based on the customers' perspectives so that PSS development is carried out in line with customer priorities. • Correlation analysis between components helps determine the impact of the development of one component on other components so that anticipatory and efficient actions can be taken. • Component analysis related to sustainability aspects can be used for the development of sustainable PSS that is component-based and convergent so that the efforts made are practical and efficient.
Components are the system constituents engineered to fulfill roles according to various design standards and patterns. PSS is a system consisting of several components. Based on the research of past studies and surveys, the PSS components include the product, the service, the actor, the relationship between stakeholders, and the technology. The results of two population tests reveal differences in the importance of technology for PSS Types 1 and 2. Additionally, there are differences in technology for PSS Types 2 and 3. As an implication, customers feel that there is a difference in the critical role of technology in PSS Type 2. There is sufficient evidence that products, services, actors, and stakeholder relationships have different levels of importance for PSS Types 1, 2, or 3. Based on the level of importance, the product is the most critical component in PSS Type 1, the technology is the most crucial component in PSS Type 2, and the service is the most critical component in PSS Type 3. The level of importance for the five PSS components is presented in Table 9. The sustainability aspects relate to products for PSS Type 1, services for PSS Type 2, and stakeholder relationships for PSS Type 3.
Limitations in this research are related to the scope of the sampling. The survey was conducted in Indonesia using a random sampling technique so that the results are not global and are therefore influenced by culture, government policies, and business ethics for companies adapted to local wisdom. In different country conditions, the level of importance of the PSS components may be different. However, this research can be repeated for global conditions, and comparative analysis can be carried out to widen the perceived benefits.