Basic Statistics

PROBLEMS 123

PROBLEMS

9.1

9.2

9.3

9.4

In Problem 7.5, use the standard deviations for bleeding times calculated from

43 bleeding times without pressure and from 39 bleeding times under pressure

to decide whether bleeding time under pressure is more variable than bleeding

time without pressure.

From Table 8.2, test if the variance of acyanotic children is significantly dif-

ferent from the variance for cyanotic children.

In Problem 7.4, there was a sample of 12 litters of mice, each consisting of 1

male and 1 female, and the data consisted of 12 pairs of weights. Why is it

inappropriate to use Table AS, the F table, on these data if we wish to find out

whether or not the variability of weights is the same among male and female

mice?

Systolic blood pressure has been measured in two groups of older people who

were not taking medication for high blood pressure. The first group of n1 = 21

persons were overweight. They had a mean systolic blood pressure of =

142 and s1 = 26. The second group of 722 = 32 was normal weight. They had

X2 = 125 and s2 = 15. Test the null hypothesis that IT: = 02” at the Q = .05

level.

Reference

van Belle, G., Fisher, L. D., Heagerty, P. J. and Lumley, T. [2004]. Biostatistics: A

Methodology for the Health Sciences, 2nd ed., Hoboken, NJ: Wiley-Interscience,

139-1 40.