On This Page:ToggleTechniquesApplicationsHow to UseAdvantagesLimitationsExample SituationQuota Sampling vs StratifiedKey Terms
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Quota sampling is a non-probabilitysampling methodwhere the researcher selects participants based on specific characteristics, ensuring they represent certain attributes in proportion to their prevalence in the population. It’s like stratified sampling but without random selection within each stratum.
Non-probability sampling means that researchers subjectively choose the sample instead of random selection, so not all population members have an equal chance of participating.
Researchers will assign quotas to a group of people in order to create subgroups of individuals that represent characteristics of the target population as a whole.
Some examples of these characteristics are gender, age, sex, residency, education level, or income. Once the subgroups are formed, the researchers will use their own judgment to select the subjects from each segment to produce the final sample.
It is important for researchers to maintain the correct proportions to represent the population. For example, if the larger population is 65% female and 35% male, the final sample should reflect these percentages.
Techniques
Controlled Quota Sampling
Uncontrolled Quota Sampling
Applications
Quota sampling is used when…
How to Use
Here’s a basic outline of how quota sampling might work in a study:
Identify Strata and Proportions
The first step in quota sampling is to identify the strata of the population. Strata are subgroups or categories within the population.
The researchers would then determine the proportions of these strata within the population, which would be the sample’s target proportions.
Select sample size
Several factors, including the population size, the margin of error, the confidence level, and the expected response distribution, determine the sample size in a research study.
Select Participants
The researchers would then select participants from each stratum until the quota for each stratum was filled.
Advantages
Quick and easy
Because the sample is representative of the population of interest, quota sampling saves data collection time. It is a quick, straightforward, and convenient way to sample data.
Cheap
Representative of target population
The goal of quota sampling is to replicate the population of interest. Researchers will aim to form a sample that effectively represents the population’s characteristics.
Limitations
Large potential for bias
Because this method involves non-random sample selection, samples can be biased, making the data less reliable.
Not generalizable to the population
While this sampling method can be very representative of the quota-defining characteristics, other important characteristics may not be represented in the final sample group.
Cannot calculate sampling error
Because quota sampling is not a probability sampling method, researchers are unable to calculate the sampling error.
Example Situation
Suppose we are conducting a study on the reading habits of high school students in a district. The district’s high school population is 45% freshmen, 25% sophomores, 20% juniors, and 10% seniors.
Real-Life Examples
Quota Sampling vs Stratified Sampling
Quota sampling and stratified sampling both involve dividing a population into mutually exclusive subgroups and sampling a predetermined number of individuals from each.
However, the most significant difference between these two techniques is that quota sampling is a non-probability sampling method, while stratified sampling is a probability sampling method.
In a stratified sample, individuals within each stratum are selected at random, while in a quota sample, researchers choose the sample as opposed to randomly selecting it.
Key Terms
References
Boston University School of Public Health. (n.d.). The role of probability. Sampling. Retrieved from https://sphweb.bumc.bu.edu/otlt/mph-modules/bs/bs704_probability/bs704_probability2.html
Guignard R, Wilquin J-L, Richard J-B, Beck F (2013) Tobacco Smoking Surveillance: Is Quota Sampling an Efficient Tool for Monitoring National Trends? A Comparison with a Random Cross-Sectional Survey. PLoS ONE 8(10): e78372. https://doi.org/10.1371/journal.pone.0078372
Im, E. O., & Chee, W. (2011). Quota sampling in internet research: practical issues. CIN: Computers, Informatics, Nursing, 29(7), 381-385.
Morrow, K.M., Vargas, S., Rosen, R.K. et al. (2007). The Utility of Non-proportional Quota Sampling for Recruiting At-risk Women for Microbicide Research. AIDS Behav 11, 586.https://doi.org/10.1007/s10461-007-9213-z
Owen, L., McNeill, A., & Callum, C. (1998). Trends in smoking during pregnancy in England, 1992-7: quota sampling surveys. Bmj, 317(7160), 728-730.
Quota sampling: Definition, types & free examples. QuestionPro. (2021, July 19). Retrieved from https://www.questionpro.com/blog/quota-sampling/
Quota Sampling. Voxco. (2021, March 12). Retrieved from https://www.voxco.com/blog/quota-sampling/
Sedgwick, P. (2012). Proportional quota sampling. BMJ, 345. https://doi.org/10.1136/bmj.e6336
Thomson, C. S., Woolnough, S., Wickenden, M., Hiom, S., & Twelves, C. J. (2010). Sunbed use in children aged 11-17 in England: face to face quota sampling surveys in the National Prevalence Study and Six Cities Study. Bmj, 340.
Further InformationTaherdoost, H. (2016). Sampling methods in research methodology; how to choose a sampling technique for research. How to Choose a Sampling Technique for Research (April 10, 2016).
Further Information
Taherdoost, H. (2016). Sampling methods in research methodology; how to choose a sampling technique for research. How to Choose a Sampling Technique for Research (April 10, 2016).
Saul McLeod, PhD
BSc (Hons) Psychology, MRes, PhD, University of Manchester
Saul McLeod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.
Olivia Guy-Evans, MSc
BSc (Hons) Psychology, MSc Psychology of Education
Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.
Julia Simkus
BA (Hons) Psychology, Princeton University
Julia Simkus is a graduate of Princeton University with a Bachelor of Arts in Psychology. She is currently studying for a Master’s Degree in Counseling for Mental Health and Wellness in September 2023. Julia’s research has been published in peer reviewed journals.
