1. Introduction
Today, digital transformation (DT) and sustainable orientation (SO) are two central pillars of Europe’s economic and political agenda. Increasingly, policymakers and scholars see them as closely connected processes that influence both economic outcomes (EO) and regional convergence in complex ways. Treating them as separate issues would hide their tightly linked dynamics: digitalization simultaneously promotes innovation while increasing environmental pressures, whereas SO requires a reevaluation of resource use amid a time when new technologies are changing production and consumption patterns [
1]. Early studies introduced the idea of “digital sustainability,” focusing on integrating social and ecological concerns into the design and use of digital infrastructures [
2,
3]. More recent research shows not only the potential of digital technologies to support the green transition but also the risks of worsening inequalities or increasing dependence on non-renewable resources [
1,
4,
5].
This ambivalence becomes especially evident in the European Union, where digital and sustainability agendas merge under the framework of the so-called “twin transition.” However, the literature highlights a series of structural paradoxes. On one hand, DT creates opportunities for new sustainable business models and enhances corporate value when paired with firm environmental commitments [
6,
7]. On the other hand, efficiency improvements often lead to rebound effects that reduce or even negate ecological benefits [
8,
9]. Comparative analyses also show that EU member countries display highly uneven levels of digital readiness and SO, which in turn create significant disparities in how these processes produce tangible results [
10].
The current study examines the systemic relationship among digital transformation (DT), sustainable orientation (SO), and economic outcomes (EO) across European Union member states. While previous research has looked at the links between the Digital Economy and Society Index (DESI) and the Sustainable Development Goals Index (SDGi), this study pushes the discussion further by analyzing how these two aspects interact to influence economic performance, measured by GDP per capita.
The analysis employs a multidimensional mixed-methods framework that combines factor analysis to identify underlying structures, generalized linear models to estimate causal effects, and cluster analysis to uncover patterns of convergence and divergence among member states. This approach goes beyond traditional correlation-based studies by capturing both the structural and dynamic relationships that define the European twin transition. The study’s originality lies in conceptualizing this transition not just as the intersection of two policy areas but as a deeply interconnected process that affects competitiveness, resilience, and long-term economic sustainability within the EU. Therefore, the paper addresses two main research questions: What is the nature of the relationship between DT, SO, and EO in the European Union? Also, how can member states be grouped based on their digital, sustainable, and economic profiles to identify patterns of convergence and divergence?
The structure of the article follows this order: the introduction sets the context and highlights the importance of the topic, then it moves to the literature review and hypothesis development, a detailed presentation of materials and methods, the results, a discussion, and finally the conclusions.
  3. Materials and Methods
  3.1. Research Design
The conceptual and empirical framework of this study is based on the idea that digital transformation (DT) and sustainable orientation (SO), although often studied separately, have combined systemic effects on economic outcomes (EO) when considered together. In the European context—marked by structural diversity and ongoing regional disparities—the research aims not only to identify direct relationships among variables but also to explore the broader patterns that develop as DT and SO interact dynamically.
The research design adopts a transnational comparative perspective focusing on EU member states from 2017 to 2024. This timeframe was selected to ensure the availability of harmonized data and to capture a period of intensified European policy efforts related to the digital and green transitions. These years also include major external shocks, such as the COVID-19 pandemic and the energy crisis, which tested the resilience and adaptability of national systems.
The selected indicators—primarily drawn from the Digital Economy and Society Index (DESI), the Sustainable Development Goals Index (SDGi), and Eurostat’s macroeconomic datasets—were chosen for their conceptual relevance, data reliability, and cross-country comparability. Together, they offer a consistent empirical foundation for assessing how digital readiness, sustainable development, and economic performance interact on a systemic level. While this set of indicators highlights key aspects of the twin transition, it naturally simplifies a complex reality, as factors like governance quality, innovation ecosystems, or institutional culture remain outside the model’s direct scope.
It is also important to recognize the limitations inherent in the cross-sectional nature of the dataset. While this design allows for a comparative snapshot of EU countries and reveals structural patterns of convergence or divergence, it does not fully capture the temporal dynamics or causal feedback mechanisms that develop over longer periods. As a result, the findings should be viewed as indicative of current structural relationships rather than conclusive evidence of long-term causality. Despite these limitations, the combination of methods and indicators offers a coherent and empirically grounded framework for analyzing how digital and sustainable transitions together influence economic outcomes across Europe.
To address the research objectives, the study employs a three-stage model. The first stage uses factor analysis to simplify data and identify underlying structures that influence the relationships between DT and SO variables. The second stage applies generalized linear models (GLM) to estimate causal links between digital and sustainable progress, on the one hand, and EO on the other. The third stage involves cluster analysis, grouping EU countries into similar categories with comparable DT-SO-EO profiles. This methodological approach improves the robustness of the research and allows for a detailed interpretation of the studied phenomenon.
Figure 1 presents the conceptual model developed by the authors.
   3.2. Selected Variables
The selection of variables depends on both their theoretical relevance and the availability of harmonized European data. Primary sources include indicators from the European Commission [
104] via the Digital Economy and Society Index (DESI), SO measures published by Sachs et al. [
105] in the Sustainable Development Goals Index (SDGi), real GDP per capita (GDPc), and the number of enterprises adopting at least one artificial intelligence technology, as reported by Eurostat [
106,
107].
Digital variables include Connectivity (CON), Digital Public Services (DPS), Human Capital (HC), and Integration of Digital Technology (IDT), representing the main dimensions of DESI and measured as standardized composite scores across the EU. Additionally, we introduce an emerging indicator, AIT, which measures the percentage of enterprises adopting at least one AI technology. Including this variable emphasizes the growing importance of AI as both a driver of digital transformation and a differentiator among European economies. It plays a key role in the cluster analysis that incorporates AI, GDP, and SDGi data for 2024.
On the SO dimension, the main variable is SDGi, a composite score that merges national progress across the SDGs. Economic success is evaluated by GDP per capita, shown as real spending per person and adjusted for purchasing power standards (PPS_EU27_2020=100). This approach guarantees comparability between countries while avoiding distortions from price differences or economic structural disparities.
Table 1 presents the variables, measures, and data sources.
 The combination of these indicators builds a strong foundation for analyzing the interaction between DT, SO, and EO, while also providing a solid basis for testing the proposed hypotheses.
  3.3. Methods
The methodological approach combines two complementary tools for testing hypothesis H1: factor analysis and generalized linear models (GLM). This combination addresses the limitations of each method individually and offers a more comprehensive understanding of the phenomenon.
Factor analysis serves as the initial step, reducing the dataset’s dimensionality and identifying latent structures [
108] that influence the relationship between digital and SO variables. The general formula for factor analysis can be expressed as (1):
—observed variables (GDPc, CON, DPS, HC, IDT, SDGi).
—matrix of factor loadings.
—latent factors.
—errors. 
This technique allows the identification of common constructs, such as a latent factor of “digital readiness” or “institutional sustainability,” while minimizing risks of redundancy and multicollinearity.
The second step uses GLM to estimate causal relationships between variables. GLM builds on traditional linear regression by incorporating link functions that capture more complex interactions between the independent variables and the dependent variable [
109]. The general formula is (2):
—dependent variable (GDPc);
—independent variables (CON, DPS, HC, IDT, SDGi);
—intercept;
—regression coefficients;
—error.
GLM thus identifies causal relationships and assesses how strongly digital and sustainable progress impact EO.
Along with these methods, the study utilizes cluster analysis to investigate hypothesis H2, grouping member states based on their DT, SO, and EO profiles. The clustering process follows Ward’s method [
110,
111], as described by the function (3):
—the center of cluster j.
—number of points in cluster j.
Δ—merging cost of combining the clusters A and B.
i—cases.
The results of this analysis reveal patterns of convergence and divergence within the European Union, showing groups of states with either similar or different paths.
This methodological approach offers a comprehensive understanding of the systemic interactions linking DT, SO, and EO. By combining traditional statistical methods with machine learning, the analysis goes beyond just quantifying effects, providing a systemic view of the mechanisms that drive convergence and divergence in the European space.
  4. Results
The factor analysis conducted in this study demonstrates the robustness of the dataset and the relevance of the variables chosen to examine the relationship between DT, SO, and EO. The correlation matrix highlights significant interdependencies among digital variables (CON, DPS, HC, and the IDT). These indicators show strong correlations both with each other and with GDP per capita (
Table 2).
The strongest link is between HC and the IDT (r = 0.797, p < 0.001). This shows that building digital skills helps to use emerging technologies. At the same time, positive links between GDP and digital indicators—especially HC and DPS—confirm that digital growth directly affects EO, although the strength of these links varies. The sustainability index is the only area with a weaker link to GDP (r = 0.129, p = 0.051), suggesting a more complex relationship likely influenced by other factors.
The application of factor analysis is justified by the KMO value of 0.708, which exceeds the minimum threshold, and Bartlett’s test, which indicates high statistical significance (χ2 = 562.192, p < 0.001). Together, these factors confirm that the dataset is suitable for uncovering underlying structures and reducing dimensionality.
The results on communalities (
Table 3) show that digital variables, especially HC and digital technology integration, are highly explained by the extracted factor, with values above 0.8. In contrast, SDGi and GDP have lower communalities (0.261 and 0.253, respectively).
This pattern indicates that the latent factor primarily captures the digital dimension of progress, while SO only partially fits into this model. The factor loadings support this interpretation (
Table 3): digital variables load very strongly (from 0.856 for DPS to 0.914 for HC), whereas GDP and the SDGi show more moderate loadings (0.503 and 0.511). This distribution suggests that EO and SO are influenced indirectly, with digital progress being the main driver within the European Union.
The table on total variance explained shows that one factor accounts for 53.19% of the total variance (
Table 4).
Although this percentage exceeds the minimum threshold for interpretability, it also shows that nearly half of the variance remains unexplained. This indicates that the phenomenon is complex and involves additional factors not captured by the model. The single factor can be viewed as a latent dimension of “digital and institutional readiness,” where SO and EO are present, though in a more subtle form.
Regarding Hypothesis H1, the results support the idea of complementarity between DT and SO in explaining EO, while also highlighting differences in their levels of influence. Digitalization emerges as the most important and influential factor, while SO plays a supporting role, somewhat embedded within the core structure. However, the strong correlations between GDP per capita and both digital indicators, and to a lesser extent, the sustainability index, confirm that digital and sustainable development are interconnected. Digitalization, though, has a more immediate impact. Therefore, H1 is supported, with the finding that DT is currently the main driver, while SO mainly contributes through indirect and mediated mechanisms. This aligns with the European context, where the twin transition does not happen in a completely symmetrical manner but shows complementarity as a clear way to enhance EO.
The generalized linear model further illustrates how DT and SO dimensions influence progress toward the SDGs, as well as EO, which is measured through GDP per capita. The tests of between-subject effects show that the models explain a significant amount of the variance in the dependent variables, with R
2 values of 0.362 for SDGi and 0.342 for GDP per capita. These findings demonstrate strong explanatory power, especially given the complexity of cross-national data (
Table 5).
For SDGi, HC is the most influential contributor, with a substantial and statistically significant effect (F = 35.701, p < 0.001). This indicates that digitally skilled and technologically adaptable human resources are key to advancing sustainable development goals. Connectivity (F = 6.918, p = 0.009) and DPS (F = 5.707, p = 0.018) also have significant, though less pronounced, effects. Meanwhile, digital technology integration shows no notable impact on SDGi.
The prominence of human capital (HC) as the only statistically significant variable in explaining both GDP per capita and SDGi outcomes highlights the mediating role of skills and digital literacy in turning technological potential into real socio-economic progress. This finding suggests that investments in education and workforce adaptability are essential for achieving the full benefits of the twin transition.
Interestingly, DPS has a negative coefficient for SDGi (B = −0.212, 
p = 0.018), suggesting potential tensions between administrative DT and SO growth, possibly caused by a focus on efficiency rather than social or environmental concerns (
Table 6).
Regarding the negative coefficient of DPS in relation to the sustainability index, the result should be interpreted with caution. One possible explanation is the efficiency-focused nature of administrative digitalization, which may initially emphasize cost savings and process improvements over inclusive or environmentally sustainable outcomes. However, this relationship might also reflect data artifacts or transitional effects common in cross-country comparisons, where rapid digitalization can temporarily coincide with lower sustainability scores due to structural or institutional mismatches. To address these limitations, we recommend that future research verify this finding through longitudinal studies or by including governance quality and institutional variables that could influence this relationship.
Turning to GDPc, the model confirms the decisive role of HC (F = 30.928, p < 0.001; B = 12.502). This result emphasizes that investments in digital skills and education directly contribute to increases in GDPc. In contrast, CON, DPS, and IDT show no significant direct effects on GDPc. This outcome indicates that merely having digital infrastructure or electronic services does not guarantee immediate economic benefits unless supported by a capable HC. The non-significant intercept for GDPc reinforces the idea that EO relies on the explanatory variables in the model, especially HC.
Taken together, these findings clarify that H1 is validated but in a nuanced way. DT and SO progress both contribute to EO, although the strength of this support varies across different dimensions. Human capital serves as the connecting element, driving both SO and EO. Connectivity and DPS play a larger role in promoting SO, although their economic effects remain indirect. Digital technology integration, however, has not yet made a significant impact, possibly due to uneven levels of digital maturity and implementation capacity across EU member states.
The GLM thus confirms H1, while emphasizing that DT mainly supports both SO and EO through HC development. This finding highlights the critical role of education and training as key areas for achieving a genuine twin transition in Europe. The factor analysis results showed a stronger clustering of digital indicators compared to sustainability and GDP variables, suggesting that the analytical model more robustly captures the digital dimension of transformation. This pattern indicates that, while digitalization serves as a primary structural driver, progress related to sustainability may follow a more indirect and context-dependent path. Accordingly, the complementarity between DT and SO observed in the model should be seen as partial and evolving rather than fully symmetrical.
Cluster analysis based on variables related to artificial intelligence use in enterprises (AIT), the sustainability index (SDGi), and GDP per capita (GDPc) reveals significant structural differences among EU member states. The results confirm the presence of patterns of convergence and divergence in the twin transition process, forming three main groups, each with its own internal logic and implications for European dynamics (
Figure 2 and 
Table A1 in 
Appendix A).
The initial group includes countries with moderate levels of digital development, as measured by the percentage of enterprises adopting AI technologies, and shows values close to the EU average for both the SDGi and GDP per capita. France, Italy, Spain, the Czech Republic, Lithuania, Cyprus, and Slovenia are part of this group, with averages of 12.83% AIT, 72.06 SDGi, and a GDP per capita of 94.63. These countries hold a balanced position where digital and sustainable sectors are fairly developed but have yet to drive significant economic growth. Their situation indicates a phase of institutional consolidation, where digital and sustainability strategies are somewhat mature but often fragmented across different administrative levels. Policy implementation is often hindered by bureaucratic inertia or inconsistent governance, which slows down turning technological capacity into broad economic progress.
The second cluster, mainly made up of Central and Eastern European countries such as Romania, Bulgaria, Hungary, Poland, and Greece, exhibits a distinct structural profile. With an average AI adoption rate of 8.58%, an SDGi of 69.15, and GDP per capita of 75.40—substantially below the EU average—these nations face persistent institutional challenges that slow down the twin transition. Although they benefit from substantial EU structural funds and ongoing digitalization initiatives, weak administrative capacity, limited absorptive ability, and inconsistent regulatory environments often weaken the impact of policy measures. However, countries like Estonia and Croatia, which are closer to the EU average, show that institutional learning and targeted reforms can gradually reduce these gaps, indicating that governance improvements are crucial in shaping national progress.
The third group includes high-performing countries such as Denmark, Sweden, Germany, Austria, Belgium, the Netherlands, and Malta. These economies have an average AI adoption rate of 22.54%, an SDGi of 74.97, and a GDP per capita of 119, which are all well above the EU average. Their success comes from strong institutional frameworks characterized by transparent governance, policy continuity, and effective collaboration between the public and private sectors. These countries have built integrated systems where digitalization policies are closely aligned with sustainability goals, creating synergies that boost innovation, competitiveness, and resilience. Ireland and Luxembourg, with outstanding GDP levels (211 and 242, respectively), are outliers that further show how institutional coherence and long-term strategic planning can enhance the effects of the twin transition.
This distribution confirms Hypothesis H2, demonstrating that EU member states can be grouped into distinct clusters based on their levels of digital transformation, sustainability orientation, and economic results (
Figure 3).
The analysis shows that structural differences are rooted not only in economic capacity but also in institutional quality, policy coordination, and governance effectiveness. Northern and Western European countries, backed by stable institutions and strategic policy alignment, lead the process, while Central and Eastern regions continue to face institutional barriers that hinder convergence. Therefore, the twin transition progresses unevenly, influenced by both institutional maturity and technological progress. The complementarity between DT and SO exists across all clusters, but its advantages are greater where governance systems are coherent and long-term planning frameworks are integrated into national strategies.
  5. Discussion
The analysis in this study offers a detailed view of the relationship between DT, SO, and EO in the European Union. Overall, the findings support both Hypothesis H1—that progress in DT and SO together helps boost GDP per capita—and Hypothesis H2, which groups European countries based on their digital, sustainable, and economic profiles. However, the observed complementarities are not consistent across all regions, as structural differences create both points of convergence and ongoing disparities.
The factor analysis indicates that the digital dimension—represented by HC, DPS, CON, and technology integration—constitutes the core of the latent factor. SO and EO are only moderately connected to this factor, suggesting that DT is the main driver of the twin transition, while SO plays a more indirect role. Practically, this implies that member states investing in digital skills, infrastructure, and technologies not only realize direct economic benefits but also build a stronger foundation for achieving sustainable development goals. Similar findings were reported by Magoutas et al. [
53], who found that digital investments directly enhance GDP growth, while their link to SO is more indirect and relies on supportive public policies. The fact that both GDP per capita and the sustainability index load onto the same latent factor, even if only moderately, echoes Harangozó and Fakó’s [
10] argument that there is a partial convergence between digital maturity and sustainable progress.
The generalized linear models improve this perspective by clarifying how complementarity develops. Human capital emerges as the most important factor for both SO and EO. Its high coefficient and strong statistical significance confirm that technological progress has little impact without people who can adopt and utilize it. This finding aligns with Brynjolfsson’s [
26] concept of the “productivity paradox,” which states that significant investments in technology do not automatically lead to economic gains unless combined with organizational changes and skilled HC. Similarly, Cardona et al. [
25] and Brynjolfsson et al. [
27] showed that the economic potential of digital technologies only becomes real when paired with investments in skills and institutions.
A particularly notable result from the GLM is the negative impact of DPS on the sustainability index. Although it may seem counterintuitive at first, this result could stem from administrative DT that emphasizes efficiency and cost-cutting while unintentionally causing social or environmental externalities that hinder sustainable development. Researchers like Alcott [
8] and York [
9] have already warned about this conflict, showing how technological advancements can lead to rebound effects that cancel out ecological gains. Similarly, Beier et al. [
24] argued that DT should be analyzed alongside SO, as examining them separately risks oversimplified conclusions. This finding supports those concerns and suggests that e-government policies need careful adjustment to avoid replacing social and ecological aspects with a purely technocratic view of progress. As discussed earlier, this unexpected negative correlation between DPS and SO may reflect transitional institutional dynamics, where rapid digitalization of administration initially prioritizes efficiency and procedural modernization over broader social and environmental goals. Over time, as governance frameworks mature and digital reforms become more inclusive, this relationship may shift toward better alignment between technological progress and sustainability outcomes.
Hypothesis H1 is therefore supported, but in a nuanced way. Digitalization and SO do contribute complementarily to GDP per capita growth, but this mainly occurs through HC rather than uniformly across all digital sectors. For example, technology integration did not show a significant effect in the model, which might indicate that these technologies are still in early stages or that their impacts only become evident after some delay.
The cluster analysis offers further insights, confirming H2 and revealing the structural polarizations within the European Union. The three identified groups show different paths of the twin transition. The cluster of Nordic and Western states, characterized by high AI adoption, strong SO scores, and superior EO, represents the ideal model of complementarity. In these countries, DT and SO not only coexist but also reinforce each other, creating significant competitive advantages. This supports the observations of Skvarciany et al. [
55], who noted that Western European countries lead the twin transition, while Central and Eastern regions continue to lag behind.
The intermediate cluster, which includes countries like France, Italy, and Spain, shows partial convergence: their levels of DT and SO are close to the EU average, while EO stays moderate. We believe these countries are in a stage of consolidation, consistent with Ricci et al. [
6] and Ukko et al. [
7], who emphasized that integrating DT and SO can boost economic value but only if supported by clear policies and strong environmental commitments.
The group of Central and Eastern European countries, characterized by low AI adoption and GDP per capita below the EU average, highlights the challenges these nations face in transforming digital development (DT) into a driver for sustainable and economic growth. This situation reflects Grybauskas et al. [
32]’s concerns about the social risks of DT, as well as those of Nosratabadi et al. [
57], who argued that DT could worsen inequalities, especially in countries with fragile infrastructure and governance.
Based on these results, H2 is confirmed: member states form distinct groups, and these groups show not only regional convergence but also persistent asymmetries. The gap between Nordic and Western states and Central and Eastern states highlights that the twin transition remains fragmented and its benefits are unevenly distributed.
Compared to the existing literature, this study offers a systemic view that emphasizes how DT and SO complement each other with varying degrees of intensity and effects shaped by HC and the institutional context. The critique of green growth by Hickel and Kallis [
34] is relevant here: DT does not guarantee sustainable progress, and SO does not always lead to significant economic growth. However, their complementarity becomes clear in high-performing clusters, showing that synergies do exist but need favorable conditions to fully develop.
  5.1. Theoretical Implications
The findings from the factor analysis, generalized linear models, and cluster analysis offer valuable contributions to the expanding literature on the European twin transition. From a theoretical perspective, the study supports the idea of complementarity between digital transformation (DT) and sustainable orientation (SO), while also showing that this relationship is neither uniform nor unconditional. The analysis confirms that human capital (HC) functions as a key mediating factor—its presence enhances the economic and sustainability outcomes of digitalization, while its absence limits them.
In this sense, the study advances the debate on Brynjolfsson’s “productivity paradox” [
26] by showing that technology alone does not ensure progress in economic or sustainable terms. Instead, it is the interaction between technological development, institutional capacity, and human adaptability that determines whether innovation benefits society. By identifying distinct clusters across Europe, the analysis enhances theoretical discussions on regional convergence and divergence, supporting Harangozó and Fakó’s [
10] argument that the twin transition remains fragmented. The research, therefore, emphasizes the need for a systemic, context-aware approach that connects digital and sustainable shifts to wider institutional dynamics.
  5.2. Empirical Interpretations
Empirically, the results show partial support for the hypothesized complementarity between DT and SO. Hypothesis H1 is confirmed, but with qualifications: while digital and sustainable dimensions jointly influence economic outcomes (EO), their effects differ significantly across indicators and regions. Human capital stands out as the most consistent and statistically significant factor affecting both GDP per capita and progress toward the Sustainable Development Goals Index (SDGi), indicating that digitalization provides tangible benefits mainly where workforce skills and adaptability are high.
On the other hand, the negative link between Digital Public Services (DPS) and sustainability, as shown in 
Section 4, indicates a complex and transitional pattern. This unexpected outcome might be due to efficiency-focused reforms that initially emphasize administrative modernization rather than inclusive or environmental goals. It could also result from temporary measurement distortions or institutional imbalances during the early phases of digital reform. These findings emphasize that complementarities are not automatic; they rely on governance quality, policy sequencing, and institutional readiness—factors that need further long-term investigation.
Hypothesis H2 is also supported, as the cluster analysis identifies three structural groups within the EU: a high-performance cluster in the North and West, a moderate group in the center, and a lagging cluster in the East and South. However, the ongoing regional disparities show that convergence is still incomplete and that institutional legacies and administrative capacity influence the twin transition as much as economic or technological factors.
  5.3. Policy Implications
The policy implications of this research must be approached with caution, given the limited timeframe and diverse dataset. Nevertheless, the findings highlight several important directions. First, the importance of human capital emphasizes that investments in digital education, reskilling, and training are essential for achieving both economic growth and sustainable development. These efforts should be regarded not as supplementary but as the foundation of competitiveness.
Second, the tensions observed between administrative digitalization and sustainability highlight the need for responsible digital governance. Efficiency and automation goals must be balanced with social inclusion and environmental responsibility, ensuring that digital reforms do not unintentionally reinforce inequality or ecological harm.
Finally, the persistence of regional disparities requires tailored policy approaches. European and national strategies must stay adaptable, recognizing diverse institutional capacities instead of enforcing one-size-fits-all solutions. Customized interventions, particularly those that strengthen local governance, innovation systems, and absorptive capacities, are crucial to ensure that the twin transition promotes cohesion rather than division.
  5.4. Limitations and Further Research
While the research design provides valuable insights, it is important to acknowledge its limitations. The study depends on a limited set of harmonized indicators (DESI, SDGi, AI adoption, and macroeconomic measures) that cannot fully represent the multidimensional nature of the twin transition. Additionally, the cross-sectional approach restricts causal inference and prevents observing long-term effects. Future research should incorporate longitudinal and sectoral perspectives to track the development of complementarities over time and across different economic sectors. Including variables related to governance quality, institutional innovation, and cultural adaptability would also enhance understanding of how digital and sustainable transitions interact.