Using risk factor surveillance as a basis for mixed-methodology research: an example from Australia using food intake and anthropometric measures.

OBJECTIVES: Risk factor surveillance is an integral part of public health, and can provide a ready-made sample for further research. This study assessed the utility of mixed-methodology research using telephone and postal surveys.
METHODS: Adult respondents to telephone surveys in South Australia and Western Australia were recruited to a postal survey about food consumption, in particular, relating to fruit and vegetables. Responses to the two surveys were compared.
RESULTS: Around 60% of eligible telephone survey respondents participated in the postal survey. There was fair to poor agreement between the results from the two methods for serves of fruit and vegetables consumed. There was excellent agreement between the two methods for self-reported height and weight.
CONCLUSIONS: The telephone survey was a useful way to recruit people to the postal survey; this could be due to the high level of trust gained through the telephone interview, or social desirability bias. It is difficult to ascertain why different results on fruit and vegetable intake were obtained, but it may be associated with understanding of the parameters of a 'serve', recall bias or the time taken to calculate an answer.