Decision Quality (Always) Increases with the Size of Information Samples--Provided that the Decision Rule Is Statistically Valid: Comment on Fiedler and Kareev (2006)

Fiedler and Kareev (2006) showed that small samples can, in principle, outperform large samples in terms of the quality of contingency-based binary choice. The 1st part of this comment critically examines these authors' claim that this small sample advantage (SSA) contradicts Bernoulli's law of large numbers and concludes that this claim is unwarranted. The 2nd part of the comment provides insight into the etiology of the SSA and points to the following as necessary conditions for the SSA's occurrence: (a) the statistical invalidity of the underlying threshold-based decision algorithm and (b) the particular payoff scheme underlying the definition of the decisions' quality. Together, these 2 factors explain how better information provided by larger samples is translated into worse decisions. (Contains 7 figures and 4 footnotes.)