The following appeared in a memorandum from the president of a company that makes shampoo.
“A widely publicized study claims that HR2, a chemical compound in our shampoo, can contribute to hair loss after prolonged use. This study, however, involved only 500 subjects. Furthermore, we have received no complaints from our customers during the past year, and some of our competitors actually use more HR2 per bottle of shampoo than we do. Therefore, we do not need to consider replacing the HR2 in our shampoo with a more expensive alternative.”
The author’s conclusion is that the company does not need to replace the HR 2 in its shampoo with a more expensive alternative. To substantiate this conclusion, the author points out that only 500 subjects were involved in the widely publicized study claiming HR 2 can contribute to hair loss after prolonged use. Also the author points out that the company has not received any complaints from customers during the past year and some of its competitors actually use more HR 2 per bottle of shampoo. Close scrutiny, however, reveals several logical flaws of this argument.
To begin with, the argument turns on the assumption that customers who did not complain were actually satisfied with the shampoo containing HR 2. However, it is not necessarily the case. Lacking more evidence, it is entirely possible that people express their displeasure simply by not purchasing such shampoo any more. The greater percentage of such people, the weaker the argument’s evidence as a sign of customer’s satisfaction with the shampoo is. Therefore, without more concrete information about the customers’ attitudes, the author cannot assume that the customers have no resistance to the shampoo.
Moreover, lacking more information about scientific study, it is unfair to claim deny the statistical reliability of the widely publicized study for it involved only 500 subjects. Probably such kind of studies require fewer participators than others. Therefore, it is entirely possible that 500 subjects are already enough to draw a convincing conclusion about the harm to hair caused by HR 2. If true, the conclusion will be seriously undermined.
