Methods of Sampling
Methods of sampling refer to the various sampling techniques that are used in collecting different types of samples in statistics. When a statistical inference needs to be made about the population, it is rarely possible to collect data of each entity belonging to that group. In such a situation, the various methods of sampling help to pick out an accurate sample from that population for analysis.
The methods of sampling can be broadly categorized into two groups, namely, non-probability and probability sampling methods. In this article, we will learn more about the different methods of sampling, their examples, and when to use such techniques.
| 1. | What are Methods of Sampling? |
| 2. | Types of Sampling |
| 3. | Probability Sampling Methods |
| 4. | Non Probability Sampling Methods |
| 5. | FAQs on Methods of Sampling |
What are Methods of Sampling?
Methods of sampling are used to pick out accurate samples that are representative of the population being analyzed. If the samples chosen for analysis are not precise then it will result in incorrect estimates of the population parameters. Thus, these sampling techniques are necessary as they enable researchers to draw inferences regarding the characteristics of the population based on the results obtained by analyzing the samples.
Types of Sampling
In order to draw valid conclusions regarding the population, choosing the correct method of sampling is key. Population refers to the entire group whose parameters need to be estimated. A sample is a specific group that forms a subset of the population and is representative of the characteristics of that population. There are two most prominent sampling techniques available in statistics. These are given as follows:
- Probability sampling methods.
- Non-probability sampling methods.
The following sections elaborate further on these methods of sampling.
Probability Sampling Methods
This method of sampling involves the random selection of any entity. In other words, each entity of such a population has an equal chance of getting selected to be part of the sample. Probability sampling methods are used in quantitative research. The aim of this sampling method is hypothesis testing. The methods of sampling that fall under this category are as follows:
Simple Random Sampling
When all the members of a population have an equally likely chance of being chosen it is known as the simple random sampling technique. A selection made using this sampling method is purely based on chance. Such a sampling technique can be conducted by using tools like a random number generator or any method that is based on only chance.
Systematic Sampling
In systematic sampling, the entities of a population are assigned a number and the individuals are chosen at regular intervals. Such a sampling technique has a predefined range as well as a set starting point and the sampling size can be repeated at regular intervals.
Stratified Random Sampling
In stratified random sampling, the researcher divides the population into non-overlapping subgroups based on a particular characteristic. The researcher calculates how many entities need to be sampled from each subgroup on the basis of the proportions of the population. Then either simple or systematic random sampling is used to choose a sample from each subgroup separately. Such a method of sampling ensures accurate representation of each subgroup.
Cluster Sampling
In this method of sampling, the researcher divides the entire population into subgroups known as clusters. Each subgroup needs to have similar attributes to the whole sample. The researcher then picks out any cluster to form the sample rather than choosing individuals at random. Such a sampling technique is used for large populations, however, it is more prone to error as each cluster could possess substantial differences with respect to each other.
Non Probability Sampling Methods
This method of sampling involves a non-random sampling technique wherein the samples are chosen based on certain criteria. This implies that not every entity has a chance of getting selected to be part of the sample. Non-probability sampling methods are used in qualitative research. However, this method of sampling is more prone to sampling bias resulting in weaker conclusions drawn about the population. The aim of this sampling method is to develop an initial understanding of the population. The different types of non-probability sampling methods are as follows:
Convenience Sampling
In convenience sampling, the collection of data from the subjects is dependent on their ease of access. In other words, the entities that are easily accessible to the researcher form the sample. This method of sampling is used when initial data needs to be gathered in a cost-effective and inexpensive way. However, the data gathered using this sampling technique may not be representative of the entire population. An example of this method of sampling is people standing at a mall and handing out flyers regarding a particular cause.
Judgemental or Purposive Sampling
Judgemental or purposive sampling is used by researchers when they need to gather data for a very specific purpose. The target audience from which the sample is chosen is based on the discretion of the researcher. This method of sampling is used when detailed knowledge of a particular phenomenon needs to be gathered. For example, suppose a researcher wants to know the experiences of disabled students. To gather this data, she will purposefully only ask students who have disabilities about their experiences.
Snowball Sampling
Snowball sampling is a type of non-probability sampling in which the researchers do not have easy access to the subjects. In such a case, they can either track a few categories to interview or they can recruit participants via other participants. This sampling technique is used when the study is based on a sensitive topic or the survey is very challenging. For example, suppose a survey is conducted on the experiences of people with HIV or AIDS. The victims might not be open to discussing their situation with a researcher. Then the snowball sampling technique is used to collect data for the sample.
Quota Sampling
In this method of sampling, the samples are created based on a certain set standard and they will have the same attributes as the entire population. Picking 5 men, 5 women, 10 girls, and 10 boys to determine how much tv they watch per day on average is an example of quota sampling.
Related Articles:
Important Notes on Methods of Sampling
- Methods of sampling are used to choose accurate samples from a population so as to represent its characteristics.
- There are two types of sampling techniques - probability and non-probability sampling.
- Probability sampling is used for hypothesis testing in quantitative research.
- Non-probability sampling is used to gather an initial understanding of the population for qualitative research.
FAQs on Methods of Sampling
What is the Meaning of Methods of Sampling in Statistics?
Methods of sampling in statistics refer to the various techniques that are used to pick out an accurate sample which will be representative of the population data's characteristics.
What are the Various Methods of Sampling?
The different methods of sampling are as follows:
- Probability sampling - simple random sampling, systematic sampling, stratified random sampling, cluster sampling.
- Non-probability sampling - Convenience sampling, purposive sampling, snowball sampling, quota sampling.
What Method of Sampling is used for Qualitative Research?
Qualitative research is usually conducted to get an initial understanding of the population before any analysis is performed. Thus, the method of sampling used is non-probability sampling.
What Sampling technique is used for Quantitative Research?
Quantitative research is concerned with conducting tests on the sample to draw inferences about the population. Thus, the probability sampling technique is used to collect samples for this purpose.
What are the Uses of the Non Probability Sampling Technique?
The non-probability sampling technique is used for creating a hypothesis, and to do exploratory research. It is usually used when there is a budget and time constraint.
What are the Uses of the Probability Method of Sampling?
The probability method of sampling is used when the sample bias needs to be reduced and the sample needs to accurately represent the population for statistical analysis.
What is the Different Between the Methods of Sampling?
The main difference between the methods of sampling is that probability sampling is used for obtaining conclusive results about the population. On the other hand, non-probability sampling is used to gather data for exploratory research.