# What is the difference between a paired t-test and a 2 sample t-test?

## What is the difference between a paired t-test and a 2 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. To use the two-sample t-test, we need to assume that the data from both samples are normally distributed and they have the same variances.

**What are the 2 types of two sample t tests?**

Calculating the Statistic / Test Types An Independent Samples t-test compares the means for two groups. A Paired sample t-test compares means from the same group at different times (say, one year apart). A One sample t-test tests the mean of a single group against a known mean.

**How do you know if a paired t-test is two tailed?**

A two-tailed test will test both if the mean is significantly greater than x and if the mean significantly less than x. The mean is considered significantly different from x if the test statistic is in the top 2.5% or bottom 2.5% of its probability distribution, resulting in a p-value less than 0.05.

### Should you use two sample t procedure on paired data?

Because the two samples are independent, you must use the 2-sample t test to compare the difference in the means. If you use the paired t test for these data, Minitab assumes that the before and after scores are paired: The 47 score before training is associated with a 53 score after training.

**What is a 2 tailed t-test?**

A two-tailed hypothesis test is designed to show whether the sample mean is significantly greater than and significantly less than the mean of a population. The two-tailed test gets its name from testing the area under both tails (sides) of a normal distribution.

**What is a two sample z-test used for?**

The z-Test: Two- Sample for Means tool runs a two sample z-Test means with known variances to test the null hypothesis that there is no difference between the means of two independent populations. This tool can be used to run a one-sided or two-sided test z-test. Two P values are calculated in the output of this test.

## How do you interpret a paired t-test?

Complete the following steps to interpret a paired t-test….

- Step 1: Determine a confidence interval for the population mean difference. First, consider the mean difference, and then examine the confidence interval.
- Step 2: Determine whether the difference is statistically significant.
- Step 3: Check your data for problems.

**What is an example of 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.

**How do you calculate t test?**

Sample question: Calculate a paired t test by hand for the following data: Step 1: Subtract each Y score from each X score. Step 2: Add up all of the values from Step 1. Step 3: Square the differences from Step 1. Step 4: Add up all of the squared differences from Step 3. Step 5: Use the following formula to calculate the t-score:

### When to use t tests?

A t-test can be used to compare two means or proportions. The t-test is appropriate when all you want to do is to compare means, and when its assumptions are met (see below). In addition, a t-test is only appropriate when the mean is an appropriate when the means (or proportions) are good measures.

**When to use the Z-test versus t-test?**

Z-test is a statistical hypothesis test that follows a normal distribution while T-test follows a Student’s T-distribution.

**What is the formula for single sample t test?**

The correct formula for the upper bound of a confidence interval for a single-sample t test is: Mupper = t(sM) + Msample. The correct formula for effect size using Cohen’s d for a single-sample t test is: d = (M – μ)/s.