Purposive Sampling – 7 Rules That You May Consider

Purposive Sampling

Purpose sampling is a very common method to get accurate results from a specific type of population. It is because, in this method of sampling, you will use particular types of people for your research instead of choosing people randomly. This can give you more precise results for your study.

In this article, we will give you seven rules you need to consider for purposive sampling.


Purposive sampling is also referred to as subjective, selective or judgmental sampling. It is a type of non-probability sampling method in which you will depend on your own judgment while selecting the individuals from a population to take part in your research. This type of sampling method requires you to get prior information and understanding of the related subject and the purpose of the study. It is because prior knowledge can help you choose properly suitable individuals as participants for your survey for conducting online surveys. If you want to analyze a specific set of people from a population, then you should use this type of sampling method to get the best results. It is because you will select the participants for your research by checking if they are fit for the study or not.

There are many benefits of using purposive sampling for a research study. Usually, the main benefit of this sampling method is that you can easily create generalizations. This means all the participants for your study will be chosen carefully according to the demands of your study. This method is very simple and straightforward. It can give you clear results to answer the main research question. All you need to do is to choose the people who see fit for your study research profile while making the sample. For instance, if you are studying iPhone marketing, then you will only choose iPhone users for your study. Nonetheless, there are various methods that you can use in this sampling method, depending upon the research objectives of your study.

Rules to follow:

Following are the rules you need to follow while using this sampling method for your study:

1.    Reasons and objectives of your research:

The first rule of doing purposive sampling is to keep the reasons and objectives of your research in mind. Before you select your research participants, you need to carefully understand why you are doing this research and what the main purpose of this research is. Try to remember the research goals you want to achieve. By keeping these things in mind, you should choose your research participants. In this way, you can get the best answers as your research participants are according to your research demands. You can also hire a PhD dissertation writing service in this regard.

2.    Diversity of target population:

You need to think about the diversity in the target population for sampling. Diversity can help you choose better research participants. The larger the diversity, the better it will be for you to choose specific people for your sampling. The level of homogeneity in the population is a huge factor in this sampling method. A population that is more homogenous will not be suitable for this type of sampling method. The random sampling method works best in a homogenous population. However, you can easily choose this sampling method for a diverse population.

3.    Choose a sample according to the degree of precision you want:

Another rule in purposive sampling is carefully considering the level of precision you want in your research. You need to think about how the precise results you want from your survey. For instance, if you want to get percentage figures from the sample, you need to consider the percentage estimations for your sampling. If you want high precision and accuracy for your research, then you need to choose a large sample size.

4.    Sample method and designs:

You also need to consider research designs and methods for purposive sampling. Choosing people for the research sample according to the method is important. Research design can help you choose your sample participants in an effective way.

5.    Budget and resources:

Another thing you need to consider is your time and resources. Their availability is very important in sampling. You need to think about how much time you can have on sampling and what the cost will be. By doing this, you can design your sample accordingly. If you have less time and resources, then choosing a small sample size is best. However, it is important to note that your approach must be able to achieve the research goals. At the end, you need to make a proper decision by doing a cost-benefit analysis. Financial ability and time considerations play a vital role in the sampling process of this method.

6.    The number of break variables:

You should also consider the number of variables for the research analysis before doing purposive sampling. For instance, if you want to study one thousand students, both male and female with five age group categories and ten other major categories, you will have 10 participants for your study on average for each combination of your categories (2×5×10 = 100 combined categories). You might realize that to study one thousand students with various responses, ten cases are not enough to get the proper results. Therefore, it is important that you select the variables of your study and then do sampling.

7.    Availability of corroborating evidence:

You should also need to consider the availability of corroborating evidence from other resources for the purposive sampling method. While using this approach for sampling, like any other sampling method, you need to consider the context. You also need to consider other evidence and the deicide to get the best answer with your sampling process. For this, you need good professional judgment and consider your research’s whole evidence collection technique.


The above guide shows all the rules you need to consider for the purposive sampling method. By keeping these rules in mind, you can decide on a perfect sample for your research. The most important thing is to keep the main research goal in mind in this sampling process.

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