Paired vs Unpaired t-test: comparison chart and examples phone survey

Paired vs. Unpaired T-Test: Comparison Chart

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In today’s world, the value of statistics is simply and undeniably unmatched. We have an abundance of data coming from huge populations, and you have to draw conclusions based on the parameters using random sampling. 

However, with importance come difficulties, and statistical methods used for such evaluations are not that simple to perform. It includes hypothesis formulation, testing, and then based on the statistical process, we decide to either accept or reject the hypothesis. 

Two such statistical hypothesis testing techniques are paired t-test and unpaired t-test. The key difference between both of them is that in a paired t-test, you compare the paired measures that match deliberately. In an unpaired t-test, you compare the means of two samples that have no natural pairing. 

But this isn’t enough to thoroughly understand both the paired t-test and the unpaired t-test. Hence, this article will compare the differences between the two using a chart.

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Difference between paired and unpaired t-tests

Here are some key differences between the two t-test methods. 

Feature 

Paired T-Test

Unpaired T-Test

Definition 

A statistical test that compares the means and standard deviations of two related samples.

A statistical test that compares the means and standard deviations of two unrelated or independent samples.

Also known as

Dependent t-test.

Independent t-test.

Hypothesis 

  • Null hypothesis H0: no significant difference between the means of two related groups.
  • Alternative hypothesis H1: there is a significant difference between the means of two related groups.
  • Null hypothesis H0: no significant difference between the means of two unrelated groups.
  • Alternative hypothesis H1: there is a significant difference between the means of two unrelated groups.

Variance

Does not assume equal variance between groups.

Assumes equal variance between groups; in case of unequal variance, use Welch’s test.

Assumptions

  • The dependent variable is normally distributed.
  • Independently sampled observations.
  • The dependent variable helps measure in ratios or intervals. 
  • Independent variables have two related or matched groups.
  • The dependent variable is normally distributed.
  • Independently sampled observations.
  • The dependent variable in the unpaired t-test helps measure ratios or intervals. 
  • The variance of data is the same between groups, meaning the groups have the same standard deviation.
  • Independent variables have two unrelated or independent groups.

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Paired v. unpaired t-test: When to use?

Both the statistical methods help compare the means of two groups. The choice of which one you should use depends on the nature of your data and the research design. 

When to use paid t-test:

Paired t-test is suitable when you want to test the same group twice or have two sets of data naturally paired. Let’s look at an example of when you can use this test. 

Market research example: 

Say you want to assess the impact of a new marketing campaign on your target customer’s purchase behavior. You start by gathering data on the amount spent by each customer before and after you launch the campaign. 

In this scenario, a paired t-test can help determine whether spending significantly increases after exposure to the campaign. 

When to use unpaired t-test:

This t-test is suitable when you have two independent groups, and you can pair each observation in one group with a unique observation in the other group. Let’s look at an example of its application in social research. 

Social research example:

Let’s say a sociologist wants to identify the differences in job satisfaction between employees in government jobs and private sector. The researcher surveys the employees from both groups and evaluates the level of job satisfaction.

For this research, unpaired t-test can help determine any significant differences in the job satisfaction level for both independent groups. 

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Paired vs. Unpaired t-test: Pros and Cons

Lets explore some advantages and disadvantages of the two t-test methods. 

Paired t-test: 

This test is useful when there is natural pairing or matching observation. 

01. Advantages: 

  • Requires small sample size.
  • Two groups have the same sample with the same abilities.

02. Disadvantages:

  • If one individual drops from the study, both the groups lose one sample as the individual share both the groups.
  • The order in which the treatment is assigned can affect the performance of the individual. He may get more used to the process and might end up performing better in the second test.

Unpaired t-test:

This type of t-test are appropriate when comparing independent groups in your research. 

01. Advantages:

  • If an individual drops the study it won’t affect the sample size of the other group.
  • As the samples are assigned randomly, the chances of the individual getting the same test are reduced and hence minimizes the effects of the potential of order with the test.

02. Disadvantages:

  • Requires a larger sample size.
  • The sample of two groups may differ in abilities, hence providing biased results.

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Working of paired and unpaired t-test with an example

For this comparison, we will take an example: a doctor wants to see how a group of people respond to the same drug. Let’s take a look at the data:

To perform a paired t-test: 

The doctor will let the group of patients take drug #1 for one month and then measure the recovery. Then have them use drug #2 and then again measure the recovery equally.

Paired vs Unpaired t-test: comparison chart and examples phone survey

Since each patient takes both the drugs, the doctor will take paired t-test and compare the mean of two tables to find out which drug is more effective.

To perform an unpaired t-test: 

The doctor will take 20 patients and randomly split them into two groups and make them take drug #1 and drug #2 separately.

Paired vs Unpaired t-test: comparison chart and examples phone survey

Since the patient in the two groups is totally different and independent, the doctor will use an unpaired t-test to see which of the group has the higher mean and determine which drug will be more effective.

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Conclusion

Understanding the differences between paired and unpaired t-test and when to use them is crucial for conducting accurate statistical analysis in your research. By selecting the appropriate test based on the experimental design and nature of the data, you can drawmeaningful conclusion and make informed decisions.

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