Problem 7E

In experiments to determine the effectiveness of drugs such as anti-fungal ointments that are applied to the skin, the concentration of the drug in a patient’s skin must be measured. The article “Determining Bio- equivalence of Topical Dermatological Drug Products by Tape-Stripping” (W. Navidi, A. Hutchinson, et al., Journal of Pharmacokinetics and Pharmacodynamics, ics,2008:213-220) describes an improved method of measuring that is designed to assure that all the drug in the skin is recovered. Assume that in an experiment using the old method, the mean amount of drug recovered from a sample of 49 patients was 105 ng with a standard deviation of 20 ng, and that in an experiment using the new method the mean amount of drug recovered in a sample of 35 patients was 117 ng with a standard deviation of 15 ng. Find a 98% confidence interval for the difference in the mean amounts recovered between the two methods.

POWERPOINT 7 ● distribution of sample means = the total number of sample means that are obtained for all of the possible random samples of a particular size (n) from a population ● we are examining the spread of our sample means ● statistics (values associated with a sample) have sampling variability associated with them ● sampling distribution = distribution of statistics obtained by selecting all the possible samples of a specific size from a population ● sample means pile up around the population mean ● sample means tend to form a normal distribution ● the larger the sample size, the closer the sample means will be to the population means ● it is virtually impossible to