Objectives: The primary objective was to compare study participation when first contact was made by telephone versus an unscheduled visit to the household. The secondary objective was to compare study participation when three differing modes of questionnaire presentation were used.
Design: The residents of 300 randomly selected households were contacted by community volunteers and asked to participate in a study of the etiology of cancer and other chronic diseases. Two methods of first contact were used, a telephone call to schedule a home visit and an unscheduled visit to the household. Three modes of questionnaire presentation were used.
Participants: Residents of a retirement community in Arizona who were aged 50 or over.
Main outcome measures: Agreement to participate, defined as acceptance of and agreement to complete the study questionnaires. Participation in the study, defined as acceptance and completion of the study questionnaires.
Results: No difference was observed in participation when first contact was made by telephone (46%) as compared with an unscheduled visit to the household (45%) (P = 0.83). Similarly, no difference in the participation was observed between three modes of presentation of the questionnaire to the householders (P = 0.13). Agreement to participate was, however, significantly higher when first contact was made by visiting the home (81% vs 55%) (P less than 0.001).
Conclusions: Neither the strategy used for first contact nor mode of questionnaire presentation affected participation.