The Assessment Phase of the Intervention Research Framework: Selecting a Study Sample

Abstract

This chapter is the second of four providing details about the Assessment phase of the Intervention Research Framework. This chapter provides details of how to describe the study population with enough detail to be meaningful to readers of the research. This chapter also details the importance and methods of selecting a study sample that is representative of the target population and therefore generalizable to the target group. Issues discussed in this chapter include: methods of selecting a random sample including a simple random sample, a systematic random sample, cluster and stratified sample, and how to use power calculations to determine sample size. Other issues discussed in this chapter include methods for random selection and allocation, and reducing non-respondent rate. A summary of the SHAHRP study sample is provided noting the study sample, inclusion and exclusion criteria, and attrition.

Objectives: By the end of this chapter readers will be able to:

• Clearly define a study population

• Identify the impact that the selection process will have on the generalizability of study results

• Identify different methods for selecting a random study sample, including simple random sample and systematic random sample

• Define cluster and stratified samples

• Understand how to determine the size of the study sample using power calculations