Example of Paired t

A physiologist wants to determine whether a particular running program has an effect on resting heart rate. The heart rates of 15 randomly selected people were measured. The people were then put on the running program and measured again one year later. Thus, the before and after measurements for each person are a pair of observations.

The physiologist performs a paired t-test to determine whether the heart rates differ before and after the running program.

Open the sample data, RestingHeartRate.MTW.
Choose Stat > Basic Statistics > Paired t.
From the drop-down list, select Each sample is in a column.
In Sample 1, enter Before.
In Sample 2, enter After.
Click OK.

Interpret the results

The null hypothesis states that the mean difference of the running times is 0. Because the p-value is 0.007, which is less than the significance level of 0.05, the physiologist rejects the null hypothesis and concludes that there is a difference between the heart rates of test subjects before and after the running program.

Descriptive Statistics

Sample	N	Mean	StDev	SE Mean
Before	20	74.50	4.51	1.01
After	20	72.30	4.05	0.91

Estimation for Paired Difference

Mean	StDev	SE Mean	95% CI for μ_difference
2.200	3.254	0.728	(0.677, 3.723)

Test

Null hypothesis	H₀: μ_difference = 0
Alternative hypothesis	H₁: μ_difference ≠ 0

T-Value	P-Value
3.02	0.007