Recruiting by registered versus standard mail

Nonresponse in population surveys is an increasing concern in health and social sciences. The magnitude of bias associated with nonresponse cannot be easily quantified or adjusted for in the estimation of prevalence and other parameters.1,2 By using various modalities, Dillman et al3 propose an evidence-based method to maximize response rates to surveys using various modalities. Sending an invitation or prenotice letter by the use of registered post or recorded delivery is cited as effective in increasing response rates for postal surveys