You do not currently have permission to view the full text for this document. Please sign in to an account with an active subscription or contact support.
In this book, which first appeared in 1935, Dr. Wechsler, with an obvious delight in numbers, has examined the range of 'scores' (defined statistically), for a great many human 'capacities', ranging from tests of intelligence and performance
to such measures as duration of pregnancy and the weight of the healthy human liver.
Wechsler finds that there are certain frequently-recurring ratios of 'best' to 'worst' performances, and that these ratios are mostly of the order of two to one. He believes that the actual range of human performance, the difference between best and worst, is very much less than popularly supposed. Further, he considers his ratios to be natural constants which are biologically determined.
Unfortunately some rather artificial statistical conditions are imposed on the raw data, such as normality of distribution, even though the normal (Gaussian) distribution is far from being the only 'natural' one. It is doubtful, too, whether his conclusions apply to the frequency of occurrence of particular mental mechanisms in different patients. Here the differences between individuals would presumably be far greater than those found by Wechsler for the 'capacities' he has examined. Nevertheless, his hypotheses are most provocative, and deserve to be tested more rigorously.