Comparison of two approaches to predicting blood donation behaviour : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Marketing at Massey University, Palmerston North
Understanding and predicting human behaviour has been of particular interest to marketers for many years. The predominant approach to predicting behaviour has relied on attitude-based models; in particular, Ajzen's (1985) theory of planned behaviour is considered the most sophisticated methodology available to researchers for behavioural prediction. However, despite much study and refinement, the predictive ability of such models remains relatively poor. Rather than continuing to rely on cognitive models, it is time to consider alternative approaches to predicting behaviour. Labaw (1980) offers one such alternative approach based on information about respondents' environment, knowledge and past behaviour. However, unlike Ajzen's theory of planned behaviour, Labaw's approach to predicting behaviour has not been widely operationalised or tested. Therefore, it is not known whether her approach, using questions that, at least theoretically, have verifiable answers, has greater predictive ability than Ajzen's theory of planned behaviour, based on attitudinal questions. This study compared the predictive ability of Ajzen's attitudinal-based theory of planned behaviour with Labaw's behavioural approach, in the context of blood donation behaviour. In absolute terms, the predictive ability of the two approaches was equivalent; however, Labaw's approach was superior to the theory of planned behaviour from a survey research perspective. Thus, Labaw's approach presents a feasible alternative to attitudinal-based approaches to predicting behaviour. This study also found that behavioural intention to donate blood was a poor predictor of actual (self-reported) donation behaviour. This finding is important given the widely-accepted assumption that the best prediction of behaviour is provided by measures of behavioural intention. In addition, the study suggests that researchers need to carefully consider the time interval selected to test the predictive ability of a model if the results are to have any practical relevance. Variables that help explain the decision to donate blood were also identified. These findings offer blood collection agencies guidance with formulating specific strategies to address blood donor shortages. However, accurately predicting who is most likely to donate blood remains problematic, and further research is needed to extend the results reported in this study.