The purpose of a study by Moneim et al was to examine thumb

The purpose of a study by Moneim et al. was to examine thumb amputations from team roping at rodeos. The researchers reviewed 16 cases of thumb amputations. Of these, 11 were complete amputations while five were incomplete. The ischemia time is the length of time that insufficient oxygen is supplied to the amputated thumb. The ischemia times (hours) for 11 subjects experiencing complete amputations were 4.67, 10.5, 2.0, 3.18, 4.00, 3.5, 3.33, 5.32, 2.0, 4.25, 6.0

For five victims of incomplete thumb amputation, the ischemia were 3.0, 10.25, 1.5, 5.22, 5.0

Treat the two reported sets of data as sample data from the populations as described. Construct a 95%confidence interval for the ratio of the two unknown population variances.

Solution

Statistics

                                  95% CI for

Variable   N StDev Variance       StDevs

Group1    11 2.363     5.582 (1.064, 6.383)

Group2     5 3.311    10.965 (1.354, 13.320)

F ratio=5.582 /10.965=0.509

Ratio of variances = 0.509

Upper limit F(4,10) value =0.11

CI Upper limit=0.509/0.11=4.627

Lower limit F(4,10) value =4.47

CI Lower limit =0.509/4.47 =0.114

95% CI = (0.114, 4.627)