Studies involving fathers: Subject refusal, attrition and sampling bias

The reported rates of subject refusal and attrition are reviewed in those studies where data were collected directly from fathers. Only 34 per cent of such studies report on subject refusal rates and 36 per cent on attrition rates. Few studies comment on or give information that would allow an assessment to be made of sampling bias arising from subject refusal and attrition. Nevertheless, studies reporting subject refusal and attrition suggest that fathers are no more difficult to recruit than mothers and that a variety of factors, individually and in combination, may have some impact on recruitment. These include the type of commitment required, the techniques of recruitment used and whether studies are hospital, home or laboratory based. However, if biases due to subject refusal and attrition are to be identified and avoided, studies need to be more open in providing information about the characteristics of refusing and participating subjects. To encourage this, some new data are presented, suggesting a number of trends: (1) extended personal contacts with potential subjects may minimize subject refusal and attrition; (2) attrition may be somewhat higher in middle-class families and families with sons.