Quota Sampling

Table of Contents

Definition:

Quota sampling is a non-probability sampling technique that involves dividing a population into strata (groups) based on pre-determined characteristics such as age, gender, income, education, or other relevant criteria. The researcher then sets a quota for each stratum, based on the proportion of the population that it represents, and selects participants until the quota is reached.

Types of Quota Sampling

Types of Quota Sampling are as follows:

Proportional quota sampling: In this method, the proportion of the quota for each stratum is the same as the proportion of that stratum in the population. For example, if 40% of the population is male and 60% is female, then the sample would be selected such that 40% are male and 60% are female.
Non-proportional quota sampling: In this method, the quotas for each stratum are not proportional to their representation in the population. For example, if 40% of the population is male and 60% is female, a non-proportional quota sample might be selected with 30% male and 70% female.
Quota sampling with replacement: In this method, after selecting a participant from a stratum, another participant from the same stratum can be selected again. This is done until the required quota is filled.
Quota sampling without replacement: In this method, once a participant is selected from a stratum, no other participant can be selected from the same stratum. This is done until the required quota is filled.
Simple quota sampling: In this method, each stratum is given an equal quota, regardless of their representation in the population. For example, if there are four strata, each stratum might be given a quota of 25% regardless of their actual representation in the population.
Sequential quota sampling: In this method, the sample is selected sequentially from each stratum until the required quota is filled. The order of selection may be predetermined or randomized.
Double quota sampling: In this method, two sets of quotas are used. One set of quotas is based on the population characteristics, and the other set is based on the sampling frame. This is done to ensure that the sample is representative of both the population and the sampling frame.
Snowball quota sampling: In this method, participants are recruited through referrals from previous participants. The quotas for each stratum are determined by the number of referrals needed to fill the quota.

Quota Sampling Methods

Quota Sampling Methods are as follows:

Telephone Quota Sampling: This method involves selecting participants based on quotas assigned to different demographic groups such as age, gender, race, income level, and geographic location. Researchers can randomly dial phone numbers to reach participants and once a person from a particular demographic group is reached and agrees to participate, no more people from that group will be contacted.
Street Intercept Quota Sampling: In this method, researchers approach people on the street and select participants based on quotas for specific demographic characteristics. For example, they may approach people and ask if they are willing to participate in a survey and select individuals based on their age, gender, or ethnicity until the required quota for each category is met.
Online Quota Sampling: This method involves selecting participants from online panels or social media platforms based on specific demographic criteria. Researchers may use a screening process to select participants based on their age, gender, income level, or other characteristics until the required quota is met.
Mall Intercept Quota Sampling: This method involves selecting participants at shopping malls, where researchers approach potential participants and ask if they are willing to participate in a survey. Participants are selected based on quotas for specific demographic characteristics.
Venue Quota Sampling: This method involves selecting participants from specific venues, such as schools, hospitals, or community centers, based on specific demographic criteria. For example, researchers may select participants from a hospital based on their age, gender, or medical condition.

Examples of Quota Sampling

Here are some examples of quota sampling:

An advertising agency wants to conduct a market research study on a new product they are launching. They decide to use quota sampling to ensure the sample is representative of the target market. They set quotas for age, gender, income, and location, and select participants from online panels based on those quotas.
A hospital wants to conduct a patient satisfaction survey. They use quota sampling to ensure the sample is representative of their patient population. They set quotas for age, gender, medical condition, and length of stay, and select participants from their patient database based on those quotas.
A political campaign wants to conduct a survey to gauge public opinion on their candidate. They use quota sampling to ensure the sample is representative of the voting population. They set quotas for age, gender, race, and political affiliation, and select participants from phone lists based on those quotas.
A university wants to conduct a survey on student satisfaction with campus life. They use quota sampling to ensure the sample is representative of the student population. They set quotas for age, gender, major, and class level, and select participants from student databases based on those quotas.
A market research firm wants to conduct a survey on consumer preferences for a new product. They use quota sampling to ensure the sample is representative of the target market. They set quotas for age, gender, income, and geographic location, and select participants from shopping malls based on those quotas.

Applications of Quota Sampling

Quota sampling is widely used in market research, social science research, and other fields where it is necessary to obtain a sample that is representative of the population of interest. Some applications of quota sampling include:

Market research: Quota sampling is commonly used in market research studies to ensure that the sample is representative of the target market. This can help companies make informed decisions about product development, advertising, and other aspects of their business.
Political polling: Quota sampling is often used in political polling to ensure that the sample is representative of the voting population. This can help political campaigns make informed decisions about campaign strategy and messaging.
Health research: Quota sampling can be used in health research studies to ensure that the sample is representative of the patient population. This can help researchers understand the prevalence and impact of different health conditions and develop effective treatments.
Education research: Quota sampling can be used in education research studies to ensure that the sample is representative of the student population. This can help researchers understand the factors that contribute to student success and develop effective educational interventions.
Social science research: Quota sampling is often used in social science research studies to ensure that the sample is representative of the population being studied. This can help researchers better understand social phenomena and develop theories to explain them.

Purpose of Quota Sampling

The purpose of quota sampling is to obtain a sample that is representative of the population of interest. This is done by selecting participants based on specific quotas for demographic characteristics such as age, gender, race, income level, and geographic location. The goal of quota sampling is to ensure that the sample reflects the diversity of the population being studied, so that the results of the study can be generalized to the population as a whole.

The purpose of quota sampling is not to obtain a statistically representative sample of the population, as is the case with probability sampling techniques such as simple random sampling or stratified random sampling. Instead, quota sampling is designed to ensure that the sample reflects the diversity of the population being studied, and can be useful in situations where other sampling techniques may not be feasible or practical.

When to use Quota Sampling

Quota sampling is a useful technique when it is difficult or impractical to obtain a random sample of the population, but it is important to obtain a sample that is representative of the population being studied. Quota sampling is typically used in situations where the research budget or time constraints do not allow for a probability sampling technique such as simple random sampling or stratified random sampling.

Quota sampling is particularly useful in the following situations:

When the population is large and diverse: It may be difficult or impractical to obtain a random sample of the entire population. In this case, quota sampling can be used to ensure that the sample reflects the diversity of the population being studied.
When the sample size is small: Probability sampling techniques require a larger sample size to achieve statistical significance. If the sample size is small, quota sampling may be a more appropriate technique to ensure that the sample is representative of the population being studied.
When time is limited: Probability sampling techniques such as simple random sampling or stratified random sampling can be time-consuming and may require significant resources. Quota sampling can be completed more quickly and efficiently, making it a good option when time is limited.
When the research budget is limited: Probability sampling techniques can be more expensive than quota sampling. In cases where the research budget is limited, quota sampling can be a more cost-effective option

Characteristics of Quota Sampling

Some characteristics of quota sampling include:

Non-random selection: Participants are not selected at random, but rather are chosen based on pre-defined quotas for certain characteristics.
Purposeful sampling: Participants are purposefully selected to ensure that the sample reflects the diversity of the population being studied.
Representative sample: The goal of quota sampling is to obtain a sample that is representative of the population being studied.
Convenience sampling: Participants are often selected based on convenience, such as their willingness to participate or their availability.
Subjectivity: The selection of participants is subjective and can be influenced by the researcher’s own biases.
Limited generalizability: The results of a quota sample may not be generalizable to the larger population, as the sample is not selected at random.
Control over sample composition: The researcher has control over the composition of the sample, as they can select participants based on pre-defined quotas.

Advantages of Quota Sampling

Quota sampling has several advantages that make it a useful technique in certain research situations. Some advantages of quota sampling include:

Cost-effective: Quota sampling is often less expensive than probability sampling techniques because it does not require complex randomization procedures or large sample sizes.
Convenient: Quota sampling is a convenient sampling method because participants can be selected based on convenience, such as their availability or willingness to participate.
Speed: Quota sampling can be completed more quickly than probability sampling techniques because the researcher can select participants based on pre-defined quotas.
Representative: Quota sampling can produce a representative sample of the population being studied because participants are selected to match certain demographic characteristics.
Flexibility: Quota sampling is flexible because the researcher can adjust the quotas to ensure that the sample is representative of the population being studied.
Useful in certain research situations: Quota sampling can be particularly useful in situations where probability sampling techniques are not feasible or practical, such as when the population is large and diverse, or when time and budget constraints are present.

Limitations of Quota Sampling

Some limitations of quota sampling include:

Non-random selection: Quota sampling does not involve random selection of participants, which means that the sample may not be representative of the population being studied.
Limited generalizability: The results of a quota sample may not be generalizable to the larger population, as the sample is not selected at random and may be subject to bias.
Potential bias: Quota sampling may introduce bias into the sample selection process, as the researcher may have subjective criteria for selecting participants based on the pre-defined quotas.
Limited control: Quota sampling provides the researcher with some control over the composition of the sample, but it may not provide as much control as other sampling techniques.
Difficult to determine sampling error: Since the sample is not selected randomly, it can be difficult to determine the sampling error, which can impact the accuracy of the results.
Limited sample size: Quota sampling may not be appropriate for larger sample sizes, as it may be difficult to find participants who meet all of the pre-defined quotas.