A stage model of blood donor behaviour: assessing volunteer behaviour.

Are there valid stages to explain blood donor behaviour? Three studies (event contingent diary, interview and psychometric) are reported that address this question. Stage and process constructs from the transtheoretical model (TTM), past behaviour and intentions are measured. The qualitative studies demonstrated that blood donors describe their behaviour using TTM constructs. The psychometric study identified: (1) groupings of blood donors consistent with Ferguson's (1996) stage predictions; (2) TTM constructs varied meaningfully as a function of these groupings; (3) associations within clusters indicated qualitatively distinct stages; and (4) TTM constructs showed incremental validity over intentions with respect to past behaviour.