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.
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.