Problem

Research on brain specimens. In Exercise 2.37 (p. 48), you learned that the postmortem int...

Research on brain specimens. In Exercise 2.37 (p. 48), you learned that the postmortem interval (PMI) is the elapsed time between death and the performance of an autopsy on the cadaver. Brain and Language (June 1995) reported on the PMIs of 22 randomly selected human brain specimens obtained at autopsy. The data are reproduced in the following table:

BRAINPMI

5.5	14.5	6.0	5.5	5.3	5.8	11.0	6.4
7.0	14.5	10.4	4.6	4.3	7.2	10.5	6.5
3.3	7.0	4.1	6.2	10.4	4.9

Source: Hayes, T. L., and Lewis, D. A. “Anatomical specialization of the anterior motor speech area: Hemispheric differences in magnopyramidal neurons,” Brain and Language, Vol. 49, No. 3, June 1995, p. 292 (Table 1).

a. Construct a 95 % confidence interval for the true mean PMI of human brain specimens obtained at autopsy.
b. Interpret the interval you found in part a.
c. What assumption is required for the interval from part a to be valid? Is this assumption satisfied? Explain.
d. What is meant by the phrase “95% confidence”?

Exercise 2.37