Sampling Methods

Probability Sampling 

Also called Random Sampling, this sampling method selects the participants randomly instead of deliberately choosing them.

Probability Sampling Methods

There are 4 types of Probability Sampling Methods used in research. These are:

• • Simple Random Sampling

• • Systematic Sampling

• • Stratified Sampling

• • Cluster Sampling

Simple Random Sampling:

• • In Simple random Sampling, every individual in the population has an equal opportunity of being selected in the sample. It can be done by keeping the identity of the people anonymous. For instance, you can assign a number to every person in the population and select numbers at random. 
  • There is no risk of bias in this sampling method because the researcher has no control over the selection process. Simple random Sampling also saves time and money and is easy to conduct.

Systematic Sampling: 

• • Systematic Sampling involves the random selection of the first person. After the first person is selected, a rule of selection is applied and every nth person is selected for the sample. 
  • For instance, you have 500 people in your population, each with a number between 1 and 500. You select the 5th person as your first choice and then apply the rule of every 10th person. 
  • The researcher can select an interval for the selection of the sample, which ensures that the selection won’t be clustered together. This also makes Systematic Sampling the least time-consuming because of the predefined range. 

Stratified Sampling:

• • This type of probability sampling method involves a random selection of samples from a predefined group (e.g. Income level). The researcher is already aware of the characteristics of the target population. The researcher stratifies it according to the characteristics in a way that serves the purpose of the research. 
  • For example, if you want to analyze people who belong to different income levels, you can use Stratified Sampling. You can create strata according to people’s monthly income- less than $3000,  $ 3000 to $5000,$5000 to $7000 and more than $7000. 
  • This way you can decide whom you want to conduct your research. However, the idea of stratifying the population adds a risk of bias.

Cluster Sampling: 

• • In the Cluster Sampling method you can divide the population into clusters or sections representing the population. These clusters have demographic characteristics like age, gender, location, etc. these are pre-existing groups. 
  • You randomly select a group rather than individuals of the population. You can include every individual from the sample cluster if it is possible. But, in case the cluster is large, you can randomly sample the individuals within each cluster and make your sample. 
  • For example, you want to research all the 10 branches of a Hotel across the country. You can’t go through all the 10 branches of the Hotel, so you can use random Sampling to select 4 Hotel branches as your cluster.