Sampling for a longitudinal study of the careers of nurses qualifying from the English pre-registration Project 2000 diploma course.

This paper describes the processes involved in selecting a sample, from the eight English regional health authorities, of nurse qualifiers from all four branches of the Project 2000 pre-registration diploma course, for a longitudinal study of nurses' careers. A simple random sample was not feasible since accurate information about the population could not be obtained and the study design involved recruiting participants by personal visit. A multi-stage approach was therefore adopted in which 'college of nursing' was taken as the primary sampling unit. Sampling was further complicated by the fact that adult branch students could generally only be visited in larger groups than was ideal. Information obtained during pilot work about the accuracy of data about the population, course completion rates and the proportion of students who were likely to agree to participate was used to calculate required sampling fractions. The final sample was therefore a function of this information and the practicalities of recruiting nurses into the study.