Understanding the purchase intentions for organic vegetables across EU: a proposal to extend the TPB model

Purpose
The study aims to propose a systematic and innovative model of purchase intention development that integrates Theory of Planned Behaviour (TPB) with its main extensions and clarifies the logical status of the variables involved and the structure of the causal path.

Design/methodology/approach
The TPB is the most useful predictive model of purchase intentions, which can be viewed as the product of various psychological determinants. Previous works have proposed extensions of the TPB model to selectively include knowledge, trust or social norms, but an integrated proposal has not yet been formulated. Based on a survey in four European countries (Germany, Italy, Poland and the UK; N = 1,035), this study tests the process of organic vegetable purchase intention development using a structural equation model (SEM). This comprises part of the measurement of latent variables and part of the analysis of dependency relationships (MLR estimation method).

Findings
The results show that purchase intention for organic vegetables is primarily dependent on positive moral attitude (PoMA) towards such consumption. The inclusion of PoMA reduces the effect of attitude toward buying organic vegetables, but the effects of social norms, past behaviour and perceived behavioural control remain significant.

Originality/value
This study proposes an innovative model to explain purchase intention for organic vegetables that incorporates the key current extensions of the TPB model (knowledge, trust and PoMA) into an integrated causal pathway. Understanding the relationships between the antecedents of purchase intention provides relevant information on “what” needs to be improved and “where” interventions are needed to steer consumers towards organic food.