Page 392 - ISC PROCEEDINGS 21.4

regression (β = 0.122, p < 0.001). This pattern is consistent with the phenomenon
of suppression, in which a variable's unique predictive contribution to the outcome is
masked in bivariate analysis due to shared variance with other predictors, particularly
Green Marketing (GM) and Influencer Endorsement (INFLU), with which SI is positively
correlated. Once these correlated variables are entered into the regression equation and
their shared variance is statistically controlled, SI's independent contribution to
sustainable purchasing behavior becomes statistically discernible (Paulhus et al., 2004).
This finding does not invalidate H4 but underscores the importance of multivariate over
bivariate inference in models with correlated predictors.
4.5. Hypothesis testing summary
Table 5. Hypothesis testing results
Hypothesis Relationship β Sig. Result
H1 P → PGP 0.201 0.000 Supported
H2 GK → PGP 0.163 0.003 Supported
H3 PQ → PGP 0.264 0.001 Supported
H4 SI → PGP 0.122 0.000 Supported
H5 GM → PGP 0.573 0.002 Supported
H6 PQ × INFLU → PGP 0.155 0.000 Supported
H7 GM × FOMO → PGP 0.620 0.000 Supported
H8 SI × FL → PGP −0.226 0.570 Not Supported
Table 5 presents the hypothesis testing results. Seven of the eight hypotheses were
supported. Among the direct antecedents, green marketing demonstrated the strongest
effect on sustainable purchasing behavior (β = 0.573, p < 0.01), followed by perceived
quality (β = 0.264, p < 0.01) and price perception (β = 0.201, p < 0.01). Social influence
and green knowledge also showed statistically significant positive effects, albeit of smaller
magnitude. Regarding the moderating hypotheses, both H6 and H7 were supported:
influencer endorsement significantly amplified the relationship between perceived quality
and purchasing behavior (β = 0.155, p < 0.001), and FOMO significantly amplified the
relationship between green marketing and purchasing behavior (β = 0.620, p < 0.001). H8,
positing that financial literacy moderates the social influence–purchasing behavior
relationship, was not supported (β = −0.226, p = 0.570).
5. Discussion
5.1. Green marketing as the dominant digital-age driver
The finding that green marketing is the strongest direct predictor of sustainable
purchasing behavior (β = 0.573) is consistent with the premise that in the digital economy,
marketing channels have become the primary touchpoint between enterprises and Gen Z
consumers. Su and Li (2025) similarly demonstrates that green advertising is a primary
driver of green purchase intention among Chinese consumers. In Vietnam's rapidly
digitizing marketplace, where social media marketing and e-commerce platforms are
dominant, this result suggests that enterprises can leverage digital green marketing as a
primary strategy for promoting sustainable products.
5.2. The amplifying role of FOMO
The significant moderating effect of FOMO on the green marketing–purchasing
behavior relationship (β = 0.620, p < 0.001) is an underexplored and practically significant
finding. This is in line with recent research demonstrating that FOMO positively affects
green consumption intention among Ho Chi Minh City's Gen Z consumers through
mediating roles of attitude and motivation (Nghiem & Tien, 2025). The result implies that

391