4.1. Measurement Model Evaluation
The measurement model was assessed to ensure reliability and validity of the constructs. The values of convergent validity and reliability for the measurement model can be seen in
Table 1. Indicator reliability was confirmed as all standardized factor loadings exceeded the recommended threshold of 0.50 [
34]. Internal consistency reliability was supported, with Composite Reliability (CR) values ranging from 0.843 to 0.895 and exceeding the minimum criterion of 0.70. Convergent validity was confirmed, with Average Variance Extracted (AVE) values between 0.520 and 0.631, surpassing the 0.50 threshold [
34]. Furthermore, Cronbach’s Alpha (CA) values for all constructs ranged from 0.766 to 0.854, which also demonstrate satisfactory reliability. Similarly, the Rho A values, which provide a more accurate estimation of construct reliability, were consistently above 0.76, further supporting the robustness of the measurement model. The loading factors for individual items varied between 0.567 and 0.846, indicating that each item contributes adequately to its respective construct. Among the constructs, GPB demonstrated the highest reliability, with a CR of 0.895 and an AVE of 0.631, while PAI, although slightly lower, still met the acceptable thresholds (CR = 0.843, AVE = 0.520). These results collectively confirm that the constructs employed in this study are both reliable and valid, thereby ensuring that subsequent structural model analysis can be performed on a solid measurement foundation.
Discriminant validity was established through the Heterotrait–Monotrait (HTMT) ratio, with all values below the threshold of 0.90 [
34]. The results of the HTMT analysis are presented in
Table 2. As shown in the table, all construct pairs exhibit HTMT values ranging from 0.360 to 0.814, which indicates adequate discriminant validity. Specifically, the highest HTMT value (0.814) was observed between EAT and EK, while the lowest value (0.360) was found between EA and PAI. Since all the values fall below the recommended cut-off point, the constructs in this study are empirically distinct from each other. This confirms that each construct measures a unique concept, thereby strengthening the validity of the measurement model. Consequently, these results provide a solid basis for proceeding with the evaluation of the structural model.
After testing the validity of the measurement model, the fitness of the measurement model was then examined based on the following indices: Chi-squared (χ2); standardized root mean square (SRMR); A value of SRMR less than 0.08 is considered a good fit [
35]. The results of the measurement model fitness are presented in
Table 3. The SRMR value obtained was 0.074, which falls below the recommended threshold, indicating that the model demonstrates an acceptable fit. Although the Chi-squared statistic (χ
2 = 1108) is significant, this is common in large sample sizes and therefore not considered a sole indicator of poor model fit. The Normed Fit Index (NFI) value was 0.799, which is slightly below the ideal threshold of 0.90 but still indicates a reasonable level of model fit. Meanwhile, the Rms Theta value was 0.128, which is within the acceptable range suggested for measurement models, reflecting that the model specification errors are minimal. Taken together, these results suggest that the measurement model demonstrates adequate overall fitness, providing confidence in the structural relationships to be tested in the subsequent analysis.
4.2. Structural Model Evaluation
Collinearity diagnostics showed that all inner Variance Inflation Factor (VIF) values were below the threshold of 5, indicating no multicollinearity issues [
31]. As presented in
Table 4, the VIF values ranged between 1.000 and 1.841, suggesting that each predictor variable contributes uniquely to the model without inflating the variance of the regression estimates. This ensures that the relationships between constructs are not biased by redundancy among predictors, thereby strengthening the robustness of the model.
The coefficient of determination (R
2) values, shown in
Table 5, provide insight into the explanatory power of the model. The model explained 43.6% of the variance in EAT (R
2 = 0.436), 55.3% of the variance in GPB (R
2 = 0.553), 37.3% of the variance in GPI (R
2 = 0.373), and 7.7% of the variance in PAI (R
2 = 0.077). According to the guidelines suggested by Hair et al. [
31], these results indicate that the explanatory power of the model is moderate for GPB, moderate-to-low for EAT and GPI, and weak for PAI. Nevertheless, the relatively higher R
2 value for GPB shows that the constructs included in the model account for more than half of the variance in green purchasing behavior, highlighting the strong predictive ability of the model in this domain.
The path analysis revealed significant relationships between EK, EAT, and PAI on GPI and GPB, providing support for most of the proposed hypotheses. As presented in
Table 6, the path from EK to EAT (H3) showed the strongest effect (β = 0.661, t = 22.423, p < 0.001), confirming that environmental knowledge plays a crucial role in shaping environmental attitude. Likewise, EAT was found to be a powerful predictor of both green purchasing intention (H4a: β = 0.445, t = 7.545, p < 0.001) and green purchasing behavior (H4b: β = 0.366, t = 9.151, p < 0.001). These findings highlight the central role of environmental attitude in translating knowledge into pro-environmental behavioral outcomes.
The influence of PAI was also noteworthy. While PAI significantly influenced GPI (H5a: β = 0.136, t = 3.259, p = 0.001), its effect on GPB was not significant (H5b: β = 0.056, t = 1.574, p = 0.116), suggesting that personal AI interaction may enhance intention but does not directly translate into actual purchasing behavior. Meanwhile, the path from GPI to GPB (H6: β = 0.444, t = 11.494, p < 0.001) was both strong and highly significant, reinforcing the Theory of Planned Behavior that intention is the most immediate antecedent of actual behavior.
Table 6 illustrates the structural model with the significance of the path coefficients. Bold black arrows represent paths significant at p < 0.01, thin black arrows indicate significance at p < 0.05, and red arrows mark unsupported hypotheses. Out of the eight tested hypotheses, seven were supported, indicating a well-fitting structural model. Overall, these results demonstrate that environmental knowledge and environmental attitude are the key drivers of green purchasing, while intention remains the strongest mediator between predictors and behavior. These findings provide theoretical support for the TPB framework and practical implications for businesses and policymakers seeking to design strategies that strengthen environmental attitudes and intentions, ultimately driving sustainable consumption behavior.
Table 6.
Structural model results.
Table 6.
Structural model results.
| Hypothesis |
Path |
β |
Tstatistics |
p-value |
Supported |
| H1 |
EK → GPI |
0.145 |
2.297 |
0.022 |
* |
| H2 |
EK → PAI |
0.278 |
5.608 |
0.000 |
*** |
| H3 |
EK → EAT |
0.661 |
22.423 |
0.000 |
*** |
| H4a |
EAT → GPI |
0.445 |
7.545 |
0.000 |
*** |
| H4b |
EAT → GPB |
0.366 |
9.151 |
0.000 |
*** |
| H5a |
PAI → GPI |
0.136 |
3.259 |
0.001 |
*** |
| H5b |
PAI → GPB |
0.056 |
1.574 |
0.116 |
- |
| H6 |
GPI → GPB |
0.444 |
11.494 |
0.000 |
*** |
4.3. Mediation Analysis
The mediating effects of GPI and PAI were tested using a bootstrapping procedure with 5,000 resamples, which is widely recommended in PLS-SEM studies to ensure robust estimation of indirect effects. As presented in
Table 7, several mediation paths were found to be statistically significant. Specifically, the path EK → EAT → GPB (β = 0.242, t = 8.424, p < 0.001) demonstrated a strong indirect effect, highlighting the crucial role of environmental attitude in linking knowledge with behavior. Similarly, the mediation path EAT → GPI → GPB (β = 0.198, t = 6.011, p < 0.001) confirmed that green purchasing intention transmits the effect of environmental attitude to actual purchasing behavior. The sequential mediation path EK → EAT → GPI → GPB (β = 0.131, t = 5.870, p < 0.001) further illustrates how environmental knowledge indirectly drives behavior through a combination of attitude and intention.
Additional significant mediation was observed in the paths EK → GPI → GPB (β = 0.064, t = 2.282, p = 0.023) and PAI → GPI → GPB (β = 0.060, t = 3.101, p = 0.002), suggesting that intention serves as a key conduit for both environmental knowledge and personal AI interaction to influence behavior. Moreover, the path EK → PAI → GPI → GPB (β = 0.017, t = 2.542, p = 0.011) was also significant, although the effect size was smaller, showing a more nuanced role of PAI in shaping behavior indirectly. In contrast, the direct mediation path EK → PAI → GPB (β = 0.016, t = 1.525, p = 0.127) was not significant, indicating that PAI alone does not translate knowledge into behavior without the involvement of intention.
Table 7.
Mediation analysis results.
Table 7.
Mediation analysis results.
| Path |
β |
T-statistics |
p-value |
Supported |
| EK → EAT → GPB |
0.242 |
8.424 |
0.000 |
*** |
| EAT → GPI → GPB |
0.198 |
6.011 |
0.000 |
*** |
| EK → EAT → GPI → GPB |
0,131 |
5.870 |
0.000 |
*** |
| EK → GPI → GPB |
0.064 |
2.282 |
0.023 |
* |
| PAI → GPI → GPB |
0.060 |
3.101 |
0.002 |
*** |
| EK → PAI → GPI → GPB |
0.017 |
2.542 |
0.011 |
* |
| EK → PAI → GPB |
0.016 |
1.525 |
0.127 |
- |
| EK → EAT → GPI |
0.294 |
7.283 |
0.000 |
*** |
| EK → PAI → GPI |
0.038 |
2.656 |
0.008 |
*** |
Table 7 presents the mediation results with the significance of the path coefficients. Bold black arrows represent indirect effects significant at p < 0.01, thin black arrows indicate effects significant at p < 0.05, and red arrows represent non-significant mediation paths. Out of the nine tested mediation paths, eight were supported, providing strong evidence for the mediating role of both environmental attitude and green purchasing intention. Overall, these findings highlight that intention plays a central mediating role, while environmental attitude strengthens the pathway from knowledge to behavior.
These mediation findings provide deeper insight into the mechanisms through which knowledge, attitude, and AI interaction shape pro-environmental purchasing. The results not only reinforce the theoretical assumptions of the TPB framework but also offer practical guidance for strategies aimed at promoting sustainable consumer behavior. The following discussion section elaborates on these theoretical and managerial implications in greater detail.
4.4. Model Predictive Performance
Predictive relevance was assessed using Stone–Geisser’s Q
2 obtained via the blindfolding procedure (Q
2 = 1 − SSE/SSO). As reported in
Table 8, the model exhibits meaningful predictive relevance for all endogenous constructs. Specifically, EAT shows Q
2 = 0.228 and GPI shows Q
2 = 0.220, both indicating medium predictive relevance, while GPB attains Q
2 = 0.337, approaching the large threshold. By contrast, EK is an exogenous construct; therefore Q
2 is not computed (shown as “–“). These results imply that the measurement–structural specification can reproduce observed data with acceptable accuracy, especially for predicting green purchasing behavior.
For interpretive clarity, note that SSO denotes the sum of squares of observations and SSE the sum of squared prediction errors; larger gaps between SSO and SSE yield higher Q2, signaling better predictive capability. In line with common benchmarks, Q2 values greater than zero indicate predictive relevance, with ≈0.02, ≈0.15, and ≈0.35 often interpreted as small, medium, and large, respectively. Hence, the current model provides medium predictive relevance for EAT and GPI and medium-to-high predictive relevance for GPB.
To complement construct-level Q2, we also inspected out-of-sample predictive performance using PLSpredict at the indicator level. The results show that for most indicators (13 out of 20), the PLS model outperforms the linear benchmark (LM), yielding higher Q2_predict (or equivalently, lower prediction errors), which corroborates the model’s practical predictive utility. Collectively, these findings confirm that the proposed model is not only explanatory (via R2) but also predictively relevant, especially for GPB—supporting the robustness of subsequent substantive interpretations and managerial implications.
Table 8.
Predictive relevance values results.
Table 8.
Predictive relevance values results.
| Construct |
SSO |
SSE |
Q2 (= 1-SSE/SSO) |
| EAT |
3072.000 |
2371.118 |
0.228 |
| EK |
2560.000 |
2560.000 |
- |
| GPB |
2560.000 |
1697.354 |
0.337 |
| GPI |
2048.000 |
1597.190 |
0.220 |
Out-of-sample predictive performance was evaluated using PLSpredict by comparing the PLS-SEM model against a linear benchmark (LM) on three metrics: item-level Q
2_predict, RMSE, and MAE. MAE captures the average absolute prediction error, while RMSE penalizes larger errors more heavily; thus, consistent reductions in both signal stronger predictive ability [
19]. As shown in
Table 9, all indicators report positive Q
2_predict values, confirming predictive relevance at the item level. Moreover, the PLS-SEM model achieves lower errors for the majority of indicators: 13 of 20 items show lower RMSE than LM and 13 of 20 show lower MAE, yielding 26 of 40 metric-item comparisons that favor PLS-SEM.
Improvements are broadly distributed across constructs. For example, several GPB and GPI indicators (e.g., Gbpe2, Gbbg1, Gpcp1, Gpib1, Gpcs1) exhibit lower RMSE and/or MAE under PLS-SEM, indicating better practical prediction of green purchasing behavior and intention. Some indicators (e.g., Eass1, Easg3, Eape1) show slightly lower errors under the LM benchmark, suggesting pockets where variance remains relatively harder to capture; however, these differences are modest and do not offset the overall advantage of PLS-SEM.
Taken together with the construct-level Q
2 results (
Table 8), these findings demonstrate that the proposed model is not only explanatory (via R
2) but also predictively useful out of sample—especially on behavior-related indicators—thereby reinforcing the robustness of the model for subsequent theoretical interpretation and managerial application.
Table 9.
RMSE and MAE Comparison (PLS-SEM vs. LM) for Predictive Performance.
Table 9.
RMSE and MAE Comparison (PLS-SEM vs. LM) for Predictive Performance.
| Items Indicator |
PLS SEM |
LM |
| Q2_predict |
RMSE |
MAE |
Q2_predict |
RMSE |
MAE |
| Ears2 |
0.145 |
0.614 |
0.516 |
0.129 |
0.619 |
0.519 |
| Eape1 |
0.319 |
0.698 |
0.530 |
0.323 |
0.696 |
0.528 |
| Easg3 |
0.169 |
0.938 |
0.734 |
0.186 |
0.929 |
0.728 |
| Eass1 |
0.285 |
0.793 |
0.631 |
0.303 |
0.783 |
0.618 |
| Eapi1 |
0.266 |
0.767 |
0.596 |
0.277 |
0.761 |
0.600 |
| Eace1 |
0.173 |
0.638 |
0.517 |
0.160 |
0.644 |
0.523 |
| Gbgm1 |
0.128 |
0.856 |
0.667 |
0.124 |
0.858 |
0.663 |
| Gbcb1 |
0.183 |
0.701 |
0.549 |
0.183 |
0.701 |
0.552 |
| Gbll1 |
0.128 |
1.003 |
0.792 |
0.138 |
0.997 |
0.787 |
| Gbbg1 |
0.110 |
0.964 |
0.756 |
0.103 |
0.967 |
0.764 |
| Gbpe2 |
0.127 |
0.892 |
0.716 |
0.116 |
0.897 |
0.726 |
| Gpis1 |
0.168 |
0.724 |
0.567 |
0.171 |
0.723 |
0.571 |
| Gpcs1 |
0.155 |
0.791 |
0.610 |
0.151 |
0.792 |
0.612 |
| Gpcp1 |
0.070 |
0.833 |
0.622 |
0.065 |
0.836 |
0.624 |
| Gpib1 |
0.132 |
0.752 |
0.572 |
0.121 |
0.757 |
0.573 |
| Pata3 |
0.036 |
0.962 |
0.793 |
0.036 |
0.962 |
0.783 |
| Papu3 |
0.014 |
0.914 |
0.728 |
0.005 |
0.919 |
0.732 |
| Paat2 |
0.024 |
0.841 |
0.647 |
0.034 |
0.837 |
0.646 |
| Paiu2 |
0.032 |
0.959 |
0.776 |
0.025 |
0.963 |
0.777 |
| Papm1 |
0.050 |
0.852 |
0.658 |
0.042 |
0.856 |
0.669 |
4.5. Summary of Findings
The results collectively support the extended TPB framework that integrates technological engagement (PAI) with psychological antecedents (EK, EAT). The measurement model was sound: all standardized loadings exceeded 0.50, CR ranged from 0.843 to 0.895, and AVE from 0.520 to 0.631; HTMT values were < 0.90, establishing discriminant validity. Model fit indices further indicated adequacy (SRMR = 0.074; NFI = 0.799; Rms Theta = 0.128). Collinearity was not a concern (inner VIFs = 1.000–1.841). On explanatory power, the structural model accounted for 43.6% of EAT, 37.3% of GPI, 55.3% of GPB, and 7.7% of PAI.
At the path level, EK strongly predicted EAT (β = 0.661, p < 0.001), and EAT predicted both GPI (β = 0.445, p < 0.001) and GPB (β = 0.366, p < 0.001). GPI also had a sizable effect on GPB (β = 0.444, p < 0.001), reaffirming intention as the most proximal driver of behavior. EK directly influenced GPI (β = 0.145, p = 0.022) and PAI (β = 0.278, p < 0.001), while PAI enhanced GPI (β = 0.136, p = 0.001) but did not directly affect GPB (β = 0.056, p = 0.116). Mediation tests (5,000 bootstraps) showed robust indirect effects via EAT and GPI—most notably EK → EAT → GPB (β = 0.242, p < 0.001), EAT → GPI → GPB (β = 0.198, p < 0.001), and the sequential EK → EAT → GPI → GPB (β = 0.131, p < 0.001)—underscoring the centrality of attitude and intention as mechanisms.
Predictively, construct-level Q2 values were positive (EAT = 0.228; GPI = 0.220; GPB = 0.337), with GPB approaching a “large” benchmark. PLSpredict showed that, at the indicator level, 26 of 40 RMSE/MAE comparisons favored the PLS-SEM model over a linear benchmark, evidencing out-of-sample utility. Overall, environmental knowledge and attitudes remain foundational, PAI primarily elevates intention (rather than behavior directly), and intention is the key gateway from cognitions to action among youth in Java.