A pilot study is run to investigate the effect of a lifestyle intervention designed to increase medication adherence in patients with HIV. Medication adherence is measured as the percentage of prescribed pills that are taken over a one-week observation period. Ten patients with HIV agree to participate and their medication adherence before and after the intervention are shown below. Compute the standard deviation of the difference in adherence before versus after the intervention.

Participant ID Before Intervention After Intervention

1 75% 79%

2 83% 84%

3 66% 70%

4 79% 68%

5 88% 90%

6 66% 78%

7 55% 60%

8 93% 90%

9 97% 90%

10 91% 95%

Please provide answer and explanation