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Stat > Basic Statistics > Paired t

Performs a paired t-test. This is appropriate for testing the mean difference between paired observations when the paired differences follow a normal distribution.

Use the Paired t command to compute a confidence interval and perform a hypothesis test of the mean difference between paired observations in the population. A paired t-test matches responses that are dependent or related in a pairwise manner. This matching allows you to account for variability between the pairs usually resulting in a smaller error term, thus increasing the sensitivity of the hypothesis test or confidence interval.

Typical examples of paired data include measurements on twins or before-and-after measurements. For a paired t-test:

H0: m d = m 0 versus H1: m d ≠ m 0

where m d is the population mean of the differences and m 0 is the hypothesized mean of the differences.

When the samples are drawn independently from two populations, use Stat > Basic Statistics > 2-sample t.

Each sample is in a column: Choose if you have entered raw data in two columns.

Sample 1: Enter the column containing the first sample

Sample 2: Enter the column containing the second sample

Summarized data (differences): Choose if you have summary values for the sample size, mean, and standard deviation of the difference.

Sample size: Enter the value for the sample size.

Sample mean: Enter the value for the mean.

Standard deviation: Enter the value for the standard deviation.