Abstract:

Leukemia is a group of blood cancers. Although stem cell donation is a curative treatment option, especially adolescents are unwilling to donate. In order to explain why some people decide to become a donor and others not, the theory of planned behavior (TPB) was used (Ajzen, 1991). According to TPB individuals’ intention (I) is a factor, which explains a particular behavior. It indicates how strongly an individual is inclined to perform a given behavior (Ajzen, 2003; 2005). Further factors that determine individuals’ intentions are attitudes (ATT), subjective norms (SN) and perceived behavioral control (PBC). In summary, the more positive a person evaluates a behavior (ATT), and the more positive their SN and PBC, the more likely they are to perform a particular behavior (Ajzen, 2005). Further model-external factors which may play a major role in predicting of intention regard stem cell donation are subject knowledge, moral obligation, moral reasoning and empathy.

In this study the mentioned TPB factors and model-external factors are examined. The research questions relate to the influence of teaching unit “Wake up” on the TPB constructs and the TPB- model-external factors. For this purpose a five-hour teaching unit is developed and conducted with 263 students of the upper secondary level. Questionnaires in pre-post design are used for data collection. To investigate which increases (defined as the change between pre- and post-test) in which factors actually explain the increases in the measured intention regarding stem cell donation, a regression analysis has been conducted.

The main findings show that model-internal factors (ATT, SN, PBC and I) and model-external factors (except empathy) increase significantly after the intervention. The results of the regression analysis show that increases in model-internal factors (ATT, SN, PBC) in particular significantly determine the increment in intention. The influence of PBC and ATT appears to be particularly strong. The increases in only these factors explain about 30% (R2adj.= ,300) of the increase in intention. If the model-external factors are considered, only moral obligation (in pre-test but not as the “increment-variable” [Difference= post- pre]) increases the predictive power of the model to 35% (R2adj.=,345). If also SN is included in the model, the extended model is able to explain about 37% of increment in intention.

The results demonstrate especially, that increases in model-internal factors predict increase in intention very well, in line with assumptions of the theory (Ajzen, 2005). In summary, it can be concluded that teaching units which target factors of TPB can also successfully promote intention. For further studies, it is necessary to investigate why the increases in model-external-factors, e.g. knowledge, do not necessarily explain the increases in intention. For this alternative treatments can be developed, tested and evaluated.

References:
[1] Ajzen, I. (1991). The theory of planned behavior. Organizational Behavior and Human Decision Processes, 50, 2, 179-211.
[2] Ajzen, I. (2003). Attitude theory and attitude-behavior relation. In D. Krebs & P. Schmidt, (Hrsg.), New Directions in Attitude Measurement. (S. 41-54). New York: WdeG.
[3] Ajzen, I. (2005). Attitudes, Personality and Behavior (2. Aufl.). New York: Open University Press.

Keywords:

Theory of planned behavior, attitudes, intention, STEM cell donation, leukemia, intervention study.