Quota Sampling

Table of contents

1. What is Quota Sampling
2. Types of Quota Sampling
3. Advantages of Quota Sampling
4. Disadvantages of Quota Sampling
5. Comparison of Quota sampling to other sampling methods

What is Quota Sampling

Quota Sampling is a non-probability sampling method in which researchers divide a certain population into certain groups basing on certain unique characteristics. The characteristics could include age, gender, income level and so on. The researchers decide the selection of sampling basing on some "quota". A "quota" is a predetermined number of individuals or elements that a researcher aims to include.

Types of Quota Sampling

There are two main types of quota sampling which are Proportional and Non-Proportional quota sampling.

Proportional Quota Sampling

Proportional quota sampling is a technique in which the quota that is selected is proportional to the actual population of the individuals in the area that the researchers are interested in. For example lets say in a classroom there are 60 girls and 40 boys. When using quota sampling, the researchers will use a ratio of 6:4 which mirrors the population of the total class. Proportional quota sampling ensures that the characteristics of the sample closely resembles the actual population. It is also straightforward and simple to implement since it involves setting quotas based on known populations.

Non-Proportional Quota Sampling

Non-proportional quota sampling on the other hand is a technique where the selected individuals do not mirror the exact population and characteristics of a certain population. Lets go back to our class example, since the class contains 60 girls and 40 boys, maybe the researchers are interested much more with the things that are related to the boys. So they will focus more or pick more boys than girls. Non-proportional quota sampling allows researchers to prioritize certain factors that are relevant to their field of research. It also allows researchers to be flexible and focus on specific groups of interests.

Advantages of Quota Sampling

• Quota sampling is cost effective as compared to other sampling techniques, especially those that require the whole population for them to be undertaken.
• Quota sampling is simple to understand and implement. It does not require complex randomization procedures making it ideal for all levels of researchers.
• Quota Sampling is much flexible in terms of selecting participants based on a certain criteria.
• Using quota sampling allows comparing subgroups easily as the quota will be broken down.

Disadvantages of Quota Sampling

• Quota sampling may lead to potential bias if the chosen population does not accurately represent the actual population
• Generalization to the actual population might be quite limited especially if the selected population does not accurately reflect the population's distribution of characteristics
• Quota sampling might become inflexible especially once the quotas have been set, it may be difficult to adjust the sample's composition during data collection

Comparison of Quota Sampling and other sampling methods

We are going to compare quota sampling to simple random sampling and stratified random sampling.

Quota Sampling vs Simple Random Sampling

Simple random sampling is a sampling technique in which every element or individual within a population has an equal chance of being selected providing an unbiased population representation. Quota sampling on the other hand can involve intentional oversampling or undersampling of certain groups which can lead to potential bias.

Quota Sampling vs Stratified Random Sampling

Stratified Random Sampling is a technique that involves dividing the population into distinct subgroups based on certain characteristics that are relevant to that type of research. Enables more detailed and precise comparisons between different strata. Quota Sampling involves setting predetermined quotas for specific characteristics, allowing intentional oversampling or undersampling. It may introduce bias if quotas are not accurately set, and the sample may not be as accurate as in stratified random sampling.

Example usage of Quota Sampling

Let us consider an example where a certain market research firm is conducting a study to understand the preferences of smartphone users in a certain city. The population consists of 10,000 smartphone users and they are categorized by their age groups: 18-25, 26-35, 36-45.

Let us important key factors:
Population Size: 10,000 users
Sample Size: The firm decides to survey at least 400 users in total
Quota Sampling Criteria: The firm wants to ensure representation from each group so they decide to set the following quotas:

• 18-25 : 50%
• 26-35: 25%
• 36-45: 25%

Procedure

1. The city is divided into geographical areas.
2. In each area, smartphone users are approached, screened based on their age groups
3. Individuals are apporached until each quota for every age group is met.
4. If any individuals who may not fit into the quotas are found, they are replaced with others who meet the criteria.
5. Then questions which cover topics such as preferred smartphone brands, features and usage patterns are asked.

Advantages of Quota Sampling in this Scenario:

• It is more affordable than surveying the entire population
• The researchers can easily implement this method without complex randomizaion procedures
• The quotas allow for comparisons between different age groups, providing aid in the analysis of preferences.

Disadvantages of Quota Sampling in this Scenario

• If smartphone users withn each age group have significantly different preferences, the sample may become biased.
• The findings may not generalize to all smartphone users in the city is certain age groups are overrepresented or underrepresented