Krieser et al. (A-17) examined glomerular filtration rate (GFR) in pediatric renal transplant recipients. GFR is an important parameter of renal function assessed in renal transplant recipients.

The following are measurements from 19 subjects of GFR measured with diethylenetriamine pentaacetic acid. (Note: some subjects were measured more than once.)

18 42 21 43 21 43 23 48 27 48 27 51 30 55 32 58 32 60 32 62 36 67 37 68 41 88 42 63 Source: Data provided courtesy of D. M. Z. Krieser, M.D.

(a) Compute mean, median, variance, standard deviation, and coefficient of variation.

(b) Construct a stem-and-leaf display.

(c) Construct a box-and-whisker plot.

(d) What percentage of the measurements is within one standard deviation of the mean? Two standard deviations? Three standard deviations?