Table 2.

Participants Required per Clinic to Detect a 4–mm Hg Difference in Systolic Blood Pressure^*

Standard Deviation of Systolic Blood Pressure	Number of Participants per Health Center Required
14	75
16	100
18	130

^*The numbers shown are the number of participants with systolic blood pressure measured at 12 months for each of 12 health centers needed to detect a 4–mm Hg difference in SBP for pair‐wise comparisons of intervention groups with usual care. Required sample sizes are reported for the given range of standard deviations, 80% power, 5% type I error, and intra–health center correlation of 0.001.