Corporate sustainability of CPA firms. Refer to the Business and Society (Mar. 2011) study on the sustainability behaviors of CPA corporations, Exercise 7.18

(p. 352). Recall that the level of support for corporate sustainability (measured on a quantitative scale ranging from 0 to 160 points) was obtained for each in a sample of 992 senior managers at CPA firms.

The accompanying MINITAB printout gives 90% confidence intervals for both the variance and standard deviation of level of support for all senior managers at CPA firms.

a. Locate the 90% confidence interval for s2 on the printout.

b. Use the sample variance on the printout to calculate the 90% confidence interval for s2. Does your result agree with the interval shown on the printout?

c. Locate the 90% confidence interval for s on the printout.

d. Use the result, part

a, to calculate the 90% confidence interval for s. Does your result agree with the interval shown on the printout?

e. Give a practical interpretation of the 90% confidence interval for s.

f. What assumption about the distribution of level of support is required for the inference, part

e, to be valid? Is this assumption reasonably satisfied?

Transcribed Image Text:

Statistics N StDev Variance Variable Support 992 26.9 722 90% Confidence Intervals Variable Method CI for StDev CI for Variance Support Chi-Square (25.9, 27.9) (672, 779)