Probability Sampling: Definition, Methods and Examples (2023)

Probability Sampling: Definition, Methods and Examples (1)

Imagine you have a population of 100 people. In this scenario, every person would have odds of 1 in 100 for getting selected. Probability sampling gives you the best chance to create a sample representative of the population. From the responses received, management will now know whether employees in that organization are happy about the amendment. Let’s talk about probability sampling.

What is Probability Sampling?

Probability sampling is a technique in which the researcher chooses samples from a larger population using a method based on probability theory. For a participant to be considered as a probability sample, he/she must be selected using a random selection.

The most critical requirement of probability sampling is that everyone in your population has a known and equal chance of getting selected.

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Probability sampling uses statistical theory to randomly select a small group of people (sample) from an existing large population and then predict that all their responses will match the overall population.

What are the Types of Probability Sampling?

Selecting the right sample is crucial for obtaining accurate and reliable results. One of the most popular and effective methods for selecting a sample is probability sampling. Let’s explore the different types of probability sampling. From simple random sampling to stratified sampling, we’ll break down each method to help you determine which one is best for your research project.

Here are some of the most effective types of probability sampling:

(Video) Sampling: Sampling & its Types | Simple Random, Convenience, Systematic, Cluster, Stratified

  1. Simple Random Sampling: This method involves randomly selecting a sample from the population without any bias. It’s the most basic and straightforward form of probability sampling.
  2. Stratified Sampling: This method involves dividing the population into subgroups or strata and selecting a random sample from each stratum. This technique is useful when the population is heterogeneous and you want to ensure that the sample is representative of different subgroups.
  3. Random Cluster Sampling: This method involves dividing the population into groups or clusters and then randomly selecting some of those clusters. This technique is useful when the population is spread out over a large geographical area, and it is not possible or practical to survey everyone.
  4. Systematic Sampling: This method involves selecting every nth member of the population after a random starting point is chosen.

Probability sampling is widely used in research because it ensures that the sample is representative of the population, allows researchers to estimate the level of uncertainty in the results, and makes it possible to generalize the findings to the population.

1. Simple Random Sampling

As the name suggests, simple random sampling is an entirely random method of selecting the sample. This sampling method is as easy as assigning numbers to the individuals (sample) and then randomly choosing from those numbers through an automated process. Finally, the numbers that are chosen are the members that are included in the sample.

There are two ways in which researchers choose the samples in this method of sampling: The lottery system and using number-generating software/ random number table. This sampling technique usually works around a large population and has its fair share of advantages and disadvantages.

Probability Sampling: Definition, Methods and Examples (2)

2. Stratified Sampling

Stratified random samplinginvolves a method where the researcher divides a more extensive population into smaller groups that usually don’t overlap but represent the entire population. While sampling, organize these groups and then draw a sample from each group separately.

A standard method is to arrange or classify by sex, age, ethnicity, and similar ways. Splitting subjects into mutually exclusive groups and then using simple random sampling to choose members from groups.

Members of these groups should be distinct so that every member of all groups get equal opportunity to be selected using simple probability. This sampling method is also called “random quota sampling.”

Probability Sampling: Definition, Methods and Examples (3)
(Video) Probability Sampling Methods

3. Random Cluster Sampling

Random cluster samplingis a way to select participants randomly that are spread out geographically. For example, if you wanted to choose 100 participants from the entire population of the U.S., it is likely impossible to get a complete list of everyone. Instead, the researcher randomly selects areas (i.e., cities or counties) and randomly selects from within those boundaries.

Probability Sampling: Definition, Methods and Examples (4)

Cluster sampling usually analyzes a particular population in which the sample consists of more than a few elements, for example, city, family, university, etc. Researchers then select the clusters by dividing the population into various smaller sections.

4. Systematic Sampling

Systematic sampling is when you choose every “nth” individual to be a part of the sample. For example, you can select every 5th person to be in the sample. Systematic sampling is an extended implementation of the same old probability technique in which each group member is selected at regular periods to form a sample. There’s an equal opportunity for every member of a population to be selected using this sampling technique.

Probability Sampling: Definition, Methods and Examples (5)

Whether you’re conducting a survey, a poll, or a study, understanding the different types of probability sampling can help you make informed decisions and achieve your research goals.

Probability Sampling Examples

Let us take an example to understand this sampling technique. The population of the US alone is 330 million. It is practically impossible to send asurveyto every individual to gather information. Use probability sampling to collect data, even if you collect it from a smaller population.

For example, an organization has 500,000 employees sitting at different geographic locations. The organization wishes to make certain amendments in its human resource policy, but before they roll out the change, they want to know if the employees will be happy with the change or not. However, reaching out to all 500,000 employees is a tedious task. This is where probability sampling comes in handy. A sample from a larger population i.e., from 500,000 employees, is chosen. This sample will represent the population. Deploy a survey now to the sample.

(Video) sampling techniques, types of sampling, probability & non probability sampling, Research methodology

From the responses received, management will now be able to know whether employees in that organization are happy or not about the amendment.

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Probability Sampling Steps

Here are some practical steps you can follow to conduct probability sampling:

  1. Choose your population of interest carefully: Carefully think and choose from the population of people you believe whose opinions should be collected and then include them in the sample.
  2. Determine a suitable sample frame:Your frame should consist of a sample from your population of interest and no one from outside to collect accurate data.
  3. Select your sample and start your survey: It can sometimes be challenging to find the proper sample and determine a suitable sample frame. Even if all factors are in your favor, there may be unforeseen issues like the cost factors, quality of respondents, and quickness to respond. Getting a sample to respond accurately to a probability survey might be difficult, but possible.

But, in most cases, drawing a probability sample will save you time, money, and a lot of frustration. You probably can’t send surveys to everyone, but you can always give everyone a chance to participate. This is what a probability sample is all about.

When to use Probability Sampling?

Use probability sampling in these instances:

Probability Sampling: Definition, Methods and Examples (6)

1. When you want to reduce the sampling bias: This sampling method is used when the bias has to be minimum. The sample selection largely determines the quality of the research’s inference. How researchers select their sample largely determines the quality of a researcher’s findings. Probability sampling leads to higher-quality findings because it provides an unbiased population representation.

2. When the population is usually diverse:Researchers use this method extensively as it helps them create samples that fully represent the population. Say we want to find out how many people prefer medical tourism over getting treated in their own country. This sampling method will help pick samples from various socio-economic strata, backgrounds, etc., representing the broader population.

(Video) Probability Sampling & Non-Probability Sampling | Research Aptitude Part-6 | Nta Net Ppr-1(unit-2).

3. To create an accurate sample:Probability sampling help researchers create accurate samples of their population. Researchers use proven statistical methods to draw a precise sample size to obtain well-defined data.

Advantages of probability sampling

Here are the advantages of probability sampling:

1. It’s Cost-effective:This process is both cost and time effective, and a larger sample can also be chosen based on numbers assigned to the samples and then choosing random numbers from the more significant sample.

2. It’s simple and straightforward:Probability sampling is an easy way of sampling as it does not involve a complicated process. It’s quick and saves time. The time saved can thus be used to analyze the data and draw conclusions.

3. It is non-technical:This sampling method doesn’t require any technical knowledge because of its simplicity. It doesn’t require intricate expertise and is not at all lengthy.

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What is the difference between probability and non-probability sampling?

Here’s how you differentiate probability sampling from non-probability sampling,

Probability sampling

Non-probability sampling

The samples are randomly selected.Samples are selected on the basis of the researcher’s subjective judgment.
Everyone in the population has an equal chance of getting selected.Not everyone has an equal chance to participate.
Researchers use this technique when they want to keep a tab on sampling bias.Sampling bias is not a concern for the researcher.
Useful in an environment having a diverse population.Useful in an environment that shares similar traits.
Used when the researcher wants to create accurate samples.This method does not help in representing the population accurately.
Finding the correct audience is complex.Finding an audience is very simple.

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(Video) Types of Sampling techniques in statistics

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What is probability sampling and example? ›

Probability sampling refers to the selection of a sample from a population, when this selection is based on the principle of randomization, that is, random selection or chance. Probability sampling is more complex, more time-consuming and usually more costly than non-probability sampling.

What is an example of probability sampling quizlet? ›

Example: We have a population that only has N=100 people in it and that you want to take a sample of n=20. To use systematic sampling, the population must be listed in a random order. The sampling fraction would be f = 20/100 = 20%. in this case, the interval size, k, is equal to N/n = 100/20 = 5.

What are the three examples of probability sampling? ›

Probability sampling methods include simple random sampling, systematic sampling, stratified sampling, and cluster sampling.

What are the 4 types of probability sampling? ›

What are the Types of Probability Sampling? There are four types of probability sampling that you can use in systematic investigations namely: simple random sampling, systematic sampling, stratified sampling, and cluster sampling.

What is a good example of probability? ›

For example, if you throw a die, then the probability of getting 1 is 1/6. Similarly, the probability of getting all the numbers from 2,3,4,5 and 6, one at a time is 1/6.

What are some examples of probability questions? ›

If two coins are tossed simultaneously, what is the probability of getting exactly two heads? From a well-shuffled deck of 52 cards, what is the probability of getting a king? In a bag, there are 5 red balls and 7 black balls. What is the probability of getting a black ball?

What is an example of a probability statement? ›

What is an example of a probability statement? A probability statement can be exact, stating something such as, "There is a 20% chance of rain in the forecast." It can also be a more general statement such as, "Rain is unlikely today."

What are examples of sampling? ›

An example of a simple random sample would be the names of 25 employees being chosen out of a hat from a company of 250 employees. In this case, the population is all 250 employees, and the sample is random because each employee has an equal chance of being chosen.

What are the 5 main types of sampling? ›

Five Basic Sampling Methods
  • Simple Random.
  • Convenience.
  • Systematic.
  • Cluster.
  • Stratified.
Jun 30, 2019

What is the most common type of probability sampling? ›

Simple Random Sample: The most basic form of probability sampling, in a simple random sample each member of a population is assigned an identifier such as a number, and those selected to be within the sample are picked at random, often using an automated software program.

What are the 3 types of events in probability? ›

The different types of events in probability are: Sure event. Impossible event. Independent events.

What is a real life example of probability distribution? ›

Probability distributions are used to describe the populations of real-life variables, like coin tosses or the weight of chicken eggs. They're also used in hypothesis testing to determine p values.

How do you solve probability questions easily? ›

Finding the probability of a simple event happening is fairly straightforward: add the probabilities together. For example, if you have a 10% chance of winning $10 and a 25% chance of winning $20 then your overall odds of winning something is 10% + 25% = 35%.

How do you write probability answers? ›

For example, the probability of flipping a coin and it being heads is ½, because there is 1 way of getting a head and the total number of possible outcomes is 2 (a head or tail). We write P(heads) = ½ . The probability of something which is certain to happen is 1.

What is probability very short answer? ›

Probability is simply how likely something is to happen. Whenever we're unsure about the outcome of an event, we can talk about the probabilities of certain outcomes—how likely they are. The analysis of events governed by probability is called statistics.

What is probability * Your answer? ›

A probability is a number that reflects the chance or likelihood that a particular event will occur. Probabilities can be expressed as proportions that range from 0 to 1, and they can also be expressed as percentages ranging from 0% to 100%.

How to calculate the probability? ›

You can use the following steps to calculate the probability of an event: Step 1: Identify an event with one result. Step 2: Identify the total number of results or outcomes and favourable outcomes that can occur. Step 3: Divide the number of favourable outcomes by the total number of possible outcomes.

How do you use probability sampling? ›

For a sampling method to be considered probability sampling, it must utilize some form of random selection. In other words, researchers must set up some process or procedure that ensures, with confidence, that the different units in their sample population have equal probabilities of being chosen.

Is lottery an example of probability sampling? ›

Detailed Solution. A lottery method is an example of simple random sampling. Simple Random Sampling: Simple random sampling is defined as a sampling technique where every item in the population has an even chance and likelihood of being selected in the sample.

What is the difference between random sampling and probability sampling? ›

Probability – or random sampling – is the random selection of sample participants to derive conclusions and assumptions about an entire population. On the other hand, non-probability sampling is the selection of sample participants based on specified criteria or suitability.

What is probability sampling give an example 10? ›

Probability sampling is based on the fact that every member of a population has a known and equal chance of being selected. For example, if you had a population of 100 people, each person would have odds of 1 out of 100 of being chosen.

How do you use sample and example? ›

“Sample”- Learn the Difference. The word example is used to mention an illustration, in support of a claim. The word sample is used to denote a specimen or model.

What are examples of samples in statistics? ›

A sample statistic (or just statistic) is defined as any number computed from your sample data. Examples include the sample average, median, sample standard deviation, and percentiles. A statistic is a random variable because it is based on data obtained by random sampling, which is a random experiment.

How do you solve probability questions? ›

Finding the probability of a simple event happening is fairly straightforward: add the probabilities together. For example, if you have a 10% chance of winning $10 and a 25% chance of winning $20 then your overall odds of winning something is 10% + 25% = 35%.

What is probability sampling formula? ›

From this database, one can easily select the probability, once the sample size and population is available. Here is the calculation – The chance of one-time selection is: P = n/N = 100/1000 = 10% And, for more than once – P = 1-(1-(1/N))nP = 1 – (999/1000)100.

What is the best probability sampling method? ›

Simple random sampling: One of the best probability sampling techniques that helps in saving time and resources is the Simple Random Sampling method. It is a reliable method of obtaining information where every single member of a population is chosen randomly, merely by chance.

Which is not an example of probability sampling *? ›

Quota sampling

This is one of the most common forms of non-probability sampling. Sampling is done until a specific number of units (quotas) for various subpopulations have been selected. Quota sampling is a means for satisfying sample size objectives for the subpopulations.

Is survey a probability sample? ›

In probability surveys (also known as sample-surveys or statistical surveys), sampling sites are selected randomly. Each sampling site represents a specific portion of the total resource or population of interest such as all river and stream length in the nation.

What is an example of stratified sampling? ›

A stratified sample is one that ensures that subgroups (strata) of a given population are each adequately represented within the whole sample population of a research study. For example, one might divide a sample of adults into subgroups by age, like 18–29, 30–39, 40–49, 50–59, and 60 and above.

What is another term for probability sampling? ›

Probability sampling is a sampling method that involves randomly selecting a sample, or a part of the population that you want to research. It is also sometimes called random sampling.

What are the benefits of probability sampling? ›

Advantages of probability sampling
  • It can reduce biases. This survey technique uses random selection, which helps reduce researcher bias and may produce results that best represent a general population.
  • It can be cost-effective. ...
  • It can be simple. ...
  • It can be time-effective.
Jul 13, 2021

Which one of the following is probability sampling? ›

Major probability sampling methods are simple random sampling, stratified random sampling, and Cluster sampling, and Systematic sampling.


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