Question

You have been analyzing discharges by sex from DRG 462, Rehabilitation, for Critical Care Hospital. Specifically, you are interested in determining if there is a difference in average age by sex. Review the data in Table 5–A–1, and answer the questions that follow.

Table 5–A–1 Mean Age of Patients by Sex, DRG 462, Rehabilitation, Critical Care Hospital, 2004

Female Male Total

N 80 88 168

Mean 55.467 53.947 54.671

Standard Deviation 17.5344 19.1981 18.3856

Standard Error 1.9604 2.0465 1.4185

Lower bound 95% CI 51.565 49.879 51.871

Upper bound 95% CI 59.370 58.015 57.472

Minimum age 19.4 17.5 17.5

Maximum age 89.1 97.6 97.6

a. State the null and alternative hypotheses; state the a priori alpha level.

b. What is the average age for the entire group? For men? For women?

c. Why is the standard error larger for the male group than for the female group?

d. Why is the standard error for the total group smaller than either of the standard errors for the male or female groups?

e. What is the 95% confidence interval for men? For women? For the entire group?

f. What is your interpretation of the 95% confidence interval?

Answer 1