One of the most important factors when it comes to collecting reliable data is sample size. In the research world, sample size—often referred to as “N”—is the number of people you sampled. For example, the total number of responses your online survey received or how many in–person interviews you conducted. Collecting responses from the appropriate number of participants will allow you to apply the results of your research properly. As such, your sample size relies heavily on your overall research goals. If you are just looking to test the waters and gather a little bit of feedback, a small sample size is generally adequate; however, if you’re looking to make some big business decisions based on the outcomes, a much larger sample size will be necessary to ensure the results are valid.
Along with your overall research goals, you’re sample size will depend, in-part, on the type of research you are doing. Most research falls into one of two broad categories: qualitative and quantitative. Quantitative research seeks information that can be expressed with numbers. A multiple-choice survey where participants are asked to rate several popular movies on a scale from one to ten is a great example of the quantitative method. Qualitative research, on the other hand, is more focused on behavior. Asking someone to rate a movie may tell you how much they liked it, but it won’t tell you why they liked it. The qualitative method seeks to fill in the gaps that arise with strictly numerical data. (Learn more about qualitative and quantitative methods here.)
When it comes to sample size, qualitative research typically requires smaller sample sizes. When doing qualitative research, the goal is to reach a point of saturation. In other words, you want to continue gathering data until the proposed research questions are sufficiently addressed but avoid the point at which interviewing more participants does not result in new findings or additional information.
Identifying sample sizes for quantitative research in a much more involved process. Determining the sample size for something like a survey, where the results will be used to make large scale business decisions—like target areas for a global marketing campaign—involves advanced statistical calculations that consider factors like desired confidence interval, confidence levels, and target population. This means that sample sizes can vary drastically. Where one project may only require 30 participants to produce statistically significant results, another might necessitate over 300.
Being sure that your research efforts provide sufficient answers to your business questions is challenging enough and finding the point at which your sample size returns significant results only adds to the difficulty—especially for those inexperienced in conducting research. This is one reason why outsourcing your research can be extremely beneficial. Working with an experienced research professional, whose main focus is getting you the answers you seek, will help keep your company on the right track and at the forefront of your industry.
Check out this article to learn more about the pros and cons of outsourcing your research.