Student Resources Study Guides and Tips The Random Selection Experiment Method By Kendra Cherry, MSEd Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book." Learn about our editorial process Updated on August 10, 2023 Fact checked Verywell Mind content is rigorously reviewed by a team of qualified and experienced fact checkers. Fact checkers review articles for factual accuracy, relevance, and timeliness. We rely on the most current and reputable sources, which are cited in the text and listed at the bottom of each article. Content is fact checked after it has been edited and before publication. Learn more. by Emily Swaim Fact checked by Emily Swaim Emily is a board-certified science editor who has worked with top digital publishing brands like Voices for Biodiversity, Study.com, GoodTherapy, Vox, and Verywell. Learn about our editorial process Print Rob Friedman / Getty Images Trending Videos Close this video player When researchers need to select a representative sample from a larger population, they often utilize a method known as random selection. In this selection process, each member of a group stands an equal chance of being chosen as a participant in the study. Random Selection vs. Random Assignment How does random selection differ from random assignment? Random selection refers to how the sample is drawn from the population as a whole, whereas random assignment refers to how the participants are then assigned to either the experimental or control groups. It is possible to have both random selection and random assignment in an experiment. Imagine that you use random selection to draw 500 people from a population to participate in your study. You then use random assignment to assign 250 of your participants to a control group (the group that does not receive the treatment or independent variable) and you assign 250 of the participants to the experimental group (the group that receives the treatment or independent variable). Why do researchers utilize random selection? The purpose is to increase the generalizability of the results. By drawing a random sample from a larger population, the goal is that the sample will be representative of the larger group and less likely to be subject to bias. Factors Involved Imagine a researcher is selecting people to participate in a study. To pick participants, they may choose people using a technique that is the statistical equivalent of a coin toss. They may begin by using random selection to pick geographic regions from which to draw participants. They may then use the same selection process to pick cities, neighborhoods, households, age ranges, and individual participants. Another important thing to remember is that larger sample sizes tend to be more representative. Even random selection can lead to a biased or limited sample if the sample size is small. When the sample size is small, an unusual participant can have an undue influence over the sample as a whole. Using a larger sample size tends to dilute the effects of unusual participants and prevent them from skewing the results. The Experimental Group In Psychology Experiments 1 Source Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Lin L. Bias caused by sampling error in meta-analysis with small sample sizes. PLoS ONE. 2018;13(9):e0204056. doi:10.1371/journal.pone.0204056 Additional Reading Elmes DG, Kantowitz BH, Roediger HL. Research Methods in Psychology. Belmont, CA: Wadsworth; 2012. By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book." See Our Editorial Process Meet Our Review Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Helpful Report an Error Other Submit