The Ultimate Guide to Random Sampling
Get a step-by-step guide for choosing the correct representative sample for survey research.
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Simple random sampling is a sampling method used in market research studies that falls under the category of probability sampling. This means that when employed, simple random sampling gives everyone in the target population an equal and known probability of being selected as a respondent in the sample group.
Simple random sampling assigns numbers to everyone within the population, so that a sample group may be selected using processes that pick random numbers from the list.
This method of sampling is most apt for when the main objective of a study is for its findings to be generalizable for a whole population. In other words, this method of sampling ensures that the data extracted from the chosen sample group is reflective of what it would be for the target population as a whole.
Simple random sampling is usually used for large populations, hence, it is important to ensure a sample size that is large enough to fittingly represent this population otherwise it will lead to increase in margin of error.
Simple random sampling ensures that all the participants have a fair chance of being chosen for the research or study.
A retail chain uses simple random sampling to assess the sales of all its branches. The retail chain company can randomly select its branches for 6 months to conduct detailed market research.
Population: In this situation, the population is all the branches of the retail company. Let’s say the retail company has 150 branches in the entire country.
Sample: With simple random sampling, the company selects 85 branches for the market research.
Data collection: To collect data, the company sends a survey to the managers of each retail branch.
Download the guide to understand step-by-step process of selecting the best sample for your next survey research
In order to use simple random sampling in a market research tool, a researcher must know the size of the population in order to ascertain the number of total units in the population. After finding the total number of units/people within the population, the researcher must then assign serial numbers to each one of them.
For example, if the study is on the employees of an organization that has 300s employees, each one of them must be assigned a number as they are the population from which the sample must be drawn.
After the numbers have been assigned, there are a few common ways in which the required sample size can be drawn from the population:
This method involves all the serial numbers being written down on chits of paper and being put into a container that is properly mixed manually. Then, chits are picked out of the container to select the sample group.
Different market research tools are used by researchers to pick a sample group. Excel and SPSS are the most common. Necessary commands must be input in regard to population size and required sample size.
Random number tables, such as the one below ranging from 000-300, can also be used. After creating a random number table with the serial numbers of your target population, you may select specific columns/rows for your sample group according to your decided sample size.
Simple random sampling can generate better results for your survey research when it is accompanies with the following
Using a survey software has a tools to conduct online surveys, CATI surveys and survey analytics can help in conducting simple random sampling studies easily. You can create a panel randomly using a survey panel manager and conduct you research by distributing the survey from the market research tool. When you have the time, resources, an omnichannel market research tool, and financial means/funding to carry it out.
When there is access to a complete list of everyone in the target population, it is simple to pick out a random sample from the complete list. It can be done using the three ways that we discussed above.
When there is a way to contact/access everyone who is selected as a respondent in the sample group, it is easy to conduct simple random sampling studies.
This method of sampling is also quite expensive, therefore in cases where cost is a primary consideration due to limited resources or funding, this isn’t a feasible sampling method.
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In stratified sampling, a researcher breaks down the targeted population into pre-define strata. The strata are built based on shared characteristics.
On the other hand, simple random sampling extracts samples from the total population irrespective of common characteristics.
Researchers use stratified sampling when a particular sub-group needs to be represented in the research.
This sampling method often leads to bias because researchers apply their reasonings to create strata.
[Read more on Stratified Sampling]
Cluster sampling has two forms – One-stage & Two-stage cluster sampling.
In one-stage cluster sampling, a researcher first creates clusters from the participant population, representing the entire population. The clusters are then randomly selected. After which sampling occurs within the selected groups.
In two-stage cluster sampling, a researcher first randomly selects a group/cluster. The participants for the research are then randomly selected from the selected cluster.
Simple random sampling selects participants from the total population, making it fundamentally different from both forms of cluster sampling.
[Read more on Cluster Sampling]
In systematic sampling, the researcher assigns all participants a number. A random starting point is determined, and an interval is set to select the first participant.
If the interval number chosen is 5, then every 5th participant is selected – 5th, 10th, 15th, 20th, 25th…, etc.
In systematic sampling, since the first participant is randomly selected, the rest of the sample is also considered random.
Simple random sampling does not have any defined starting point.
In this sampling method, the selection of participants can start from anywhere across the entire population.
[Read more on Systematic Sampling]
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Probability sampling refers to selecting participants or samples from the target population for research.
Simple random sampling is a process in which a number is assigned to every participant within the population. Then participants for the research are picked in random order.
This process gives every participant an equal probability of being selected.
There are four types of probability sampling: