Variation in the protection periods of repellents on individual human subjects: an analytical review.

Mosquito repellent test data from the literature were analyzed to estimate mean protection periods and among-subjects standard deviations. Standard deviations were a linear function of the means. Numbers of subjects needed to determine mean protection periods of 1-8 h with confidence limits of +/- 0.5, 1.0, 1.5, and 2.0 h at the 99 and 95% levels of confidence were computed from regression values of the standard deviation, and a table of sample sizes was constructed for use in planning repellent tests.