A physiological psychologist developed a drug that she thought would revolutionize the world of horse racing. She named the drug Speedo, and it was her contention that this drug would lead horses to...

A physiological psychologist developed a drug that she thought would revolutionize the world of horse racing. She named the drug Speedo, and it was her contention that this drug would lead horses to run much faster than they do now. (For the sake of this hypothetical problem, we are ignoring the fact that it is illegal to give drugs to racehorses.) She selected two groups of horses and gave one of the groups injections of Speedo once a week for 4 weeks. Because Speedo was known to have some negative effects on the horses’ digestive systems, those horses given the Speedo had to be placed on a special high-protein diet. Those horses not given the Speedo were maintained on their regular diet. After the 4-week period, all the horses were timed in a 2-mile race and the mean (average) times for the horses given Speedo were significantly faster than the mean times for those not given Speedo. The psychologist concluded that her drug was effective.

A Identify the independent variable of interest (and its levels) and a potentially relevant independent variable with which the primary independent variable is confounded. Explain clearly how the confounding occurred.

B State exactly what conclusion about the effect of the drug Speedo can be supported by the evidence presented.

C Finally, suggest ways in which the study could be done so that you could make a clear conclusion about the effectiveness of the drug Speedo.