19.    Why must I specify the number of research participants in my protocol? The application must specify the number of study participants to be recruited and tested, grouped by age, gender, and population diversity. This assures a representative research sample and prevents aggressive over recruitment. Exceeding the recruitment limits agreed to by the IRB is a protocol violation unless the IRB gives written permission.

If it is difficult to predict how many participants will be eligible or be attracted to a study, the optimum number should be specified. Responses such as "don't know" or "as many as we can recruit" to questions about the number of participants are not acceptable. A discussion of the problems faced in recruiting participants should be included.

Multicenter studies, in which data will be pooled and recruitment may vary, present a special problem for investigators. The application should provide information about the total picture, including both the number of participants to be studied at the University or by University researchers and information on overall recruiting.