There is a constant margin of error wherever measurement of human b ings is involved

There is a constant margin of error wherever measurement of human b ings is involved. The error is increased when qualities or characteristics of h man personality are subjected to measurement or when inferences about the opulation are made from measurements derived from statistical samples.
When comparisons or contrasts are made, a mere number difference i not in itself a valid basis for any conclusion. A test of statistical significance s ould be employed to weigh the possibility that chance in sample selection ould have yielded the apparent difference. To apply these measures of stati tical significance is to remove some of the doubt from the conclusions.