Growth hormone Gh is severely elevated in subjects with acromegaly, a condition that causes enlarged and deformed bone growth, particularly in the face and jaw of adults. Although Gh is thought to...

Growth hormone Gh is severely elevated in subjects with acromegaly, a condition that causes enlarged and deformed bone growth, particularly in the face and jaw of adults. Although Gh is thought to exert its effects via another hormone, insulin-like growth factor—somatomedin-C (Igf ), a close correlation between Gh and Igf has not been demonstrated. Because the body secretes Gh in cycles that have well-defined daily peaks, whereas Igf is secreted continuously, Barkan and coworkers* postulated that the lack of correlation may be due to the differences in timing of secretion. They measured blood Gh every 10 or 20 minutes for 24 hours in 21 subjects with acromegaly. As part of their analysis, they looked at the relationship between Igf and Gh at a single time point, 8 AM. Analyze these data (in Table D-13, Appendix D). A. Is there a good correlation between the blood levels of these two hormones? If not, how can one reconcile a poor correlation with the known physiological relationship between Igf and Gh? B. Does the presence of influential points alter the basic biological conclusion? C. How can a point have a large leverage, yet a low Cook’s distance?

Table D-13