How to determine sample size?

When planning a survey, determining the sample size is an important decision. Since several different factors must be considered, there is no set formula that can tell us what the perfect sample size should be. However, in general survey practice, the sample size used in a study is determined based on the expense of data collection, along with the need to have sufficient statistical power.

Things to remember:

Your research objectives and planned analytical approach should be kept in mind when deciding your sample size. Also, if the target population shows large variability in the behaviors and attitudes of interest being researched, a large sample is needed.

Before determining a survey’s sample size, we need to ask ourselves these questions:

What type of data or data analysis will be conducted?

  • How much error is tolerable?
  • How much accuracy do we need?
  • What is the research budget?
  • Can we afford the desired sample?
  • What is the population size? Large? Small/limited?

As you can see, sample size is not easily determined so caution is advised. Before making your final decision, consider different permutations and combinations and undertake a thorough analysis.