A sampling technique by which every member of the population is selected with a random start

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Definition: Random sampling is a part of the sampling technique in which each sample has an equal probability of being chosen. A sample chosen randomly is meant to be an unbiased representation of the total population. If for some reasons, the sample does not represent the population, the variation is called a sampling error.

Description: Random sampling is one of the simplest forms of collecting data from the total population. Under random sampling, each member of the subset carries an equal opportunity of being chosen as a part of the sampling process. For example, the total workforce in organisations is 300 and to conduct a survey, a sample group of 30 employees is selected to do the survey. In this case, the population is the total number of employees in the company and the sample group of 30 employees is the sample. Each member of the workforce has an equal opportunity of being chosen because all the employees which were chosen to be part of the survey were selected randomly. But, there is always a possibility that the group or the sample does not represent the population as a whole, in that case, any random variation is termed as a sampling error.

An unbiased random sample is important for drawing conclusions. For example when we took out the sample of 30 employees from the total population of 300 employees, there is always a possibility that a researcher might end up picking over 25 men even if the population consists of 200 men and 100 women. Hence, some variations when drawing results can come up, which is known as a sampling error. One of the disadvantages of random sampling is the fact that it requires a complete list of population. For example, if a company wants to carry out a survey and intends to deploy random sampling, in that case, there should be total number of employees and there is a possibility that all the employees are spread across different regions which make the process of survey little difficult.

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The secret to minimizing biased data!

A sampling technique by which every member of the population is selected with a random start

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Introduction

“Why should I care about random sampling?”

Here’s why you should know about random sampling.

If you’re a data scientist and want to develop models, you need data.

And if you need data, SOMEONE needs to collect data.

And if someone is collecting data, they need to make sure that it is not biased or it will be extremely costly in the long run.

Therefore, if you want to collect unbiased data, then you need to know about random sampling!

What exactly is random sampling?

Random sampling simply describes when every element in a population has an equal chance of being chosen for the sample.

Sounds simple right? Unfortunately, it’s a lot easier said than done. This is because there are a lot of logistics that need to be considered in order to minimize the amount of bias.

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Random Sampling Techniques

There are 4 types of random sampling techniques:

1. Simple Random Sampling

Simple random sampling requires using randomly generated numbers to choose a sample. More specifically, it initially requires a sampling frame, a list or database of all members of a population. You can then randomly generate a number for each element, using Excel for example, and take the first n samples that you require.

A sampling technique by which every member of the population is selected with a random start

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To give an example, imagine the table on the right was your sampling frame. Using a software like Excel, you can then generate random numbers for each element in the sampling frame. If you need a sample size of 3, then you would take the samples with the random numbers from 1 to 3.

2. Stratified Random Sampling

Stratified random sampling starts off by dividing a population into groups with similar attributes. Then a random sample is taken from each group.

A sampling technique by which every member of the population is selected with a random start

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This method is used to ensure that different segments in a population are equally represented. To give an example, imagine a survey is conducted at a school to determine overall satisfaction. It might make sense here to use stratified random sampling to equally represent the opinions of students in each department.

3. Cluster Random Sampling

Cluster sampling starts by dividing a population into groups, or clusters. What makes this different that stratified sampling is that each cluster must be representative of the population. Then, you randomly selecting entire clusters to sample.

A sampling technique by which every member of the population is selected with a random start

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For example, if an elementary school had five different grade eight classes, cluster random sampling might be used and only one class would be chosen as a sample, for example.

4. Systematic Random Sampling

Systematic random sampling is a very common technique in which you sample every k’th element. For example, if you were conducting surveys at a mall, you might survey every 100th person that walks in, for example.

If you have a sampling frame then you would divide the size of the frame, N, by the desired sample size, n, to get the index number, k. You would then choose every k’th element in the frame to create your sample.

A sampling technique by which every member of the population is selected with a random start

Using the same example, if we wanted a desired sample size of 2 this time, then we would take every 3rd row in the sampling frame.

Thanks for Reading!

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If you made it to the end, you should now have an understanding of what random sampling is and several techniques that are commonly used to conduct it. This is extremely important to minimize bias, and thus, create better models.

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Which is a technique of selecting random sampling?

Simple random sampling is a type of probability sampling in which the researcher randomly selects a subset of participants from a population. Each member of the population has an equal chance of being selected.

What do you call the sampling technique in which each member of the population is given equal chance to be chosen as part of the sample?

Simple random sampling In a simple random sample, every member of the population has an equal chance of being selected. Your sampling frame should include the whole population. To conduct this type of sampling, you can use tools like random number generators or other techniques that are based entirely on chance.

Which of the following sampling technique is done by selecting every element in your population list?

Random sampling simply describes when every element in a population has an equal chance of being chosen for the sample.

In which sampling method only first unit is selected as random?

Systematic random sampling is a probability sampling method that involves first randomly selecting a subject/unit from the population, then selecting further units based upon some pre-defined interval.