Biology: Concepts and Investigations 2nd Edition by Mariëlle Hoefnagels

Exercise 11

For each of the following examples, state whether each of the following faults occurred: (I) experimental evidence does not support conclusions; (II) inadequate controls; (III) biased sampling; (IV) inappropriate extrapolation from the experimental group to the general population; (V) sample size too small. a) "I ran 4 miles every morning when I was pregnant with my first child," the woman told her physician, "and Jamie weighed only half as much as a normal baby. This time, I didn't exercise at all, and Jamie's sister had normal birth weight. Therefore, running during pregnancy must cause low birth weight." b) Eating foods high in cholesterol was found to be dangerous for a large sample of individuals with hypercholesterolemia, a disorder of the heart and blood vessels. It was concluded from this study that all persons should limit dietary cholesterol intake. c) Osteogenesis imperfecta (OI) is an inherited condition that causes easily fractured bones. In a clinical study, 30 children with OI were given a new drug for 3 years. The children all showed less fatigue, improved bone density, and a lowered incidence of fractures compared with before treatment began. The conclusion: the drug is effective in treating OI. d) Researchers studied HIV in blood and semen from 11 HIV-infected men. In eight of the men, the virus was resistant to several medications. In two men, virus from the blood was resistant to the class of drugs called protease inhibitors, but virus from semen was not resistant. The researchers concluded that protease inhibitors do not reach the male reproductive organs.