# What is the difference between paired and two-sample t-test?

## What is the difference between paired and two-sample t-test?

Two-sample t-test is used when the data of two samples are statistically independent, while the paired t-test is used when data is in the form of matched pairs.

What is a paired two-sample t-test?

The Paired Samples t Test compares the means of two measurements taken from the same individual, object, or related units. These “paired” measurements can represent things like: A measurement taken at two different times (e.g., pre-test and post-test score with an intervention administered between the two time points)

### What does the t-test allow you to compare between 2 groups?

One of the most common tests in statistics, the t-test, is used to determine whether the means of two groups are equal to each other. The assumption for the test is that both groups are sampled from normal distributions with equal variances.

When would you use the t-test to compare two sample statistics?

When can I use the test? You can use the test when your data values are independent, are randomly sampled from two normal populations and the two independent groups have equal variances.

#### When should I use a paired t-test?

A paired t-test is used when we are interested in the difference between two variables for the same subject. Often the two variables are separated by time.

What is the difference between paired and unpaired t-test?

A paired t-test is designed to compare the means of the same group or item under two separate scenarios. An unpaired t-test compares the means of two independent or unrelated groups. In an unpaired t-test, the variance between groups is assumed to be equal. In a paired t-test, the variance is not assumed to be equal.

## When should you use a paired t-test?

How do you know when to use a paired t-test?

A paired t-test is used when we are interested in the difference between two variables for the same subject. Often the two variables are separated by time. For example, in the Dixon and Massey data set we have cholesterol levels in 1952 and cholesterol levels in 1962 for each subject.

### Should I use paired or unpaired t-test?

Paired t-test: Used to compare the means of two samples when each individual in one sample also appears in the other sample. Unpaired t-test: Used to compare the means of two samples when each individual in one sample is independent of every individual in the other sample.

Which test can be used to compare the two means?

t-test
A t-test is a type of inferential statistic used to determine if there is a significant difference between the means of two groups, which may be related in certain features. The t-test is one of many tests used for the purpose of hypothesis testing in statistics. Calculating a t-test requires three key data values.

#### What is meant by paired t-test?

The paired t-test gives a hypothesis examination of the difference between population means for a set of random samples whose variations are almost normally distributed. Subjects are often tested in a before-after situation or with subjects as alike as possible.

What is an example of a paired t test?

Statistical difference between two time points

• Statistical difference between two conditions
• Statistical difference between two measurements
• Statistical difference between a matched pair
• ## How to do a paired t test?

Perform the paired t-test in R using the following functions : t_test ()[rstatix package]: the result is a data frame for easy plotting using the ggpubr package.

• Interpret and report the paired t-test
• Add p-values and significance levels to a plot
• Calculate and report the paired t-test effect size using Cohen’s d.
• What are the assumptions of a paired t test?

Independence of the observations. Each subject should belong to only one group.

• No significant outliers in the two groups.
• Normality. the data for each group should be approximately normally distributed.
• Homogeneity of variances. the variance of the outcome variable should be equal in each group.
• ### When is it appropriate to use the paired difference t-test?

The paired t -test is a method used to test whether the mean difference between pairs of measurements is zero or not. When can I use the test? You can use the test when your data values are paired measurements. For example, you might have before-and-after measurements for a group of people.