INTUITIONS ABOUT SAMPLE-SIZE - THE EMPIRICAL-LAW OF LARGE NUMBERS

According to Jacob Bernoulli, even the 'stupidest man' knows that the larger one's sample of observations, the more confidence one can have in being close to the truth about the phenomenon observed. Two-and-a-h alf centuries later, psychologists empirically tested people's intuiti ons about sample size. One group of such studies found participants at tentive to sample size; another found participants ignoring it. We sug gest an explanation for st substantial part of these inconsistent find ings. We propose the hypothesis that human intuition conforms to the ' empirical law of large numbers' and distinguish between two kinds of t asks - one that can be solved by this intuition (frequency distributio ns) and one for which it is not sufficient (sampling distributions). A review of the literature reveals that this distinction can explain a substantial part of the apparently inconsistent results. (C) 1997 by J ohn Wiley & Sons, Ltd.