А. [Representativeness heuristic] Insensitivity to sample size | мельница полного самоизмельчения

А. [Representativeness heuristic] Insensitivity to sample size

Consider an example is of two hospitals of differing size. Approximately 45 babies are born in the large hospital while 15 babies are born in the small hospital. Half (50%) of all babies born in general are boys. However, the percentage changes from one day to another. For a 1-year period, each hospital recorded the days on which >60% of the babies born were boys. The question posed is: Which hospital do you think recorded more such days?

— The larger hospital;
— The smaller hospital;
— About the same (that is, within 5% of each other).

The results show that more than half the respondents selected the wrong answer (third option). This is due to the respondents ignoring the effect of sample size. The respondents selected the third option most likely because the same statistic represents both the large and small hospitals. According to statistical theory, a small sample size allows the statistical parameter to deviate considerably compared to a large sample. Therefore, the large hospital would have a higher probability to stay close to the nominal value of 50%.