The following appeared in a memo from the director of a large group of hospitals.
“In a controlled laboratory study of liquid hand soaps, a concentrated solution of extra strength UltraClean hand soap produced a 40 percent greater reduction in harmful bacteria than did the liquid hand soaps currently used in our hospitals. During our recent test of regular-strength UltraClean with doctors, nurses, and visitors at our hospital in Worktown, the hospital reported significantly fewer cases of patient infection (a 20 percent reduction) than did any of the other hospitals in our group. Therefore, to prevent serious patient infections, we should supply UltraClean at all hand-washing stations, including those used by visitors, throughout our hospital system.”
Write a response in which you discuss what specific evidence is needed to evaluate the argument and explain how the evidence would weaken or strengthen the argument.
Both of the claims in the argument rely on the results of a single study, which, while apparently impressive, is flawed. First, the results of the study are skewed toward increasing the strength of the soap used. The follow-up study was done after the study was completed, and the results show, as expected, that the concentration of the soap actually increased the number of bacteria. Therefore, the fact that a 40 percent reduction in bacteria was found is not surprising, since higher concentrations would have more bacterial reduction. More importantly, however, is the fact that no attempt was made to check whether the soaps actually reduced the amount of bacteria on the hands. If the soap left germs behind, then the test would have been ineffective.
Second, the study used only one hospital. It is conceivable that because the study focused on one hospital, the results were not representative. The director claims that the rate of infection was lower at the hospital in the study. This may be true, but that needs to be verified. Also, the directors claim that ‘the hospital reported significantly fewer cases of patient infection’ should be supported by statistics, which the study does not supply. The director provides no evidence for this claim; it only states it. To bolster this claim, it would be necessary to obtain statistics for the hospitals in the director’s group that show the rate of infection and compare it to the rate of infection at the hospital in the study. This would involve obtaining data from each hospital on what percentage of patients get an infection and comparing those numbers.
The director also states that the results of the study warrant the use of UltraClean throughout the hospital system, but does not consider the fact that many other hospitals are not in her group. She claims that ‘the hospital reported significantly fewer cases of patient infection’, but this needs verification. If this is true, then hospitals outside the director’s group may want to follow in her footsteps and switch to using UltraClean since the rates of infection are lower. However, if the rates of infection are not lower, then the use of UltraClean may result in more infections, not fewer.
The director’s recommendations are reliant on the results of a single study, which, while apparently impressive, is flawed. Therefore, the results of this study cannot be used to justify a recommendation to use UltraClean throughout the hospital system.