What Is a Representative Sample?

And Why They Are So Important in Research

Representative sample checklist
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A representative sample is a group of participants selected from a larger population that closely matches the characteristics of the population as a whole. In other words, the sample is a fairly accurate reflection of the population from which the sample is drawn.

Why does this matter? What impact does a representative sample have on research? Let's take a closer look at some of the key reasons why scientists use this important technique in their research.

Why Use a Representative Sample?

When collecting data for psychological studies, researchers rarely gather information from every single member of a particular population. Doing so would be exceedingly laborious - not to mention incredibly expensive. There are some instances where it is important to collect data from every member of a population (the U.S. census is one example). In most cases, researchers instead rely on a sample that represents the group as a whole.

While it may sound fairly straightforward, obtaining a truly representative sample can be quite challenging and requires a great deal of time and effort. One of the first issues that researchers face is trying to get a smaller sample of participants that truly reflects what is going on in the larger population. 

The larger the sample is, the more likely it will accurately reflect what exists in the population as a whole. Imagine, for example, that you were trying to create a sample that accurately represents the entire population of the United States.

This might be very tough to do if your sample is too small because you want to represent the variety of people present in terms of age, sex, ethnicity, race, religion, sexual orientation, and other key variables. In order to obtain a truly representative sample, you might need to gather information from a fairly large pool of individuals.

 

How Are Representative Samples Obtained?

In psychology, a representative sample is a selected segment of a group that closely parallels the population as a whole in terms of the key variables and characteristics that are under examination. Some of the factors that researchers consider when selecting a representative sample include sex, age, educational level, socioeconomic status, and marital status.

For example, if roughly half of the total population of interest is female, a sample should be made up of approximately 50 percent women in order to be representative.

By selecting a representative sample, researchers are then better able to generalize the results of their studies and experiments to the population as a whole.

Random sampling is often utilized to obtain a representative sample from a larger group. This involves randomly selecting who will be in the sample. Every member of the population stands and equal chance of being selected. This method can lead to quite accurate results, but if the sample is biased in some way, it can lead to results that do not reflect the group as a whole.

Examples of Representative Samples

Imagine that researchers want to look at differences in eye color in the United States. In order to obtain a representative sample, they need to look at what percentage of U.S. citizens share certain qualities such as ethnic background and gender and ensure that their sample accurately reflects those numbers.

Recent census statistics suggest that 77.4 percent of Americans are white, 13.2 percent are black, 1.2 percent are American Indians or Alaskan Natives, 5.4 percent are Asian and 17.4 percent are Hispanic. The survey also found that women represent 50.8 percent of the total population. In order to obtain a representative sample in the eye color study, the sample drawn from the total population should accurately reflect these numbers.

So Why Are Representative Samples So Important in Health Research?

So what happens when a sample is not representative?

Websites, magazines, and organizations often conduct their own polls and questionnaires on a range of topics. While the results of such surveys might be representative of their readership or membership, such results are probably quite biased and not accurate reflections of the larger population.

Why? Because those individuals are already different in some way from the larger group through their affiliation with that source. Readers of Family Circle magazine are probably going to have different interests than readers of Maxim magazine. If both publications conducted reader surveys on a specific issue, the results would probably be considerably different.

For this reason, it is important that samples in scientific research accurately represent the population that researchers are attempting to study.

Imagine if scientists wanted to study the prevalence of a particular disease in the population at large. If they were to rely on a non-representative sample, they might reach conclusions that do not accurately reflect what is really going on in the world. This might ultimately end up impacting how much further research is devoted to the study of that illness as well as how much funding might be available for additional research into prevention and treatment.

Sources:

Coon, D. & Mitterer, J. O. (2010). Introduction to psychology: Gateways to mind and behavior with concept maps. Belmont, CA: Wadsworth; 2010.

U.S. Census Bureau. Quick Facts: United States; 2015.

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