FIGURE 11.3
In Theory, Most People Are Average Almost 70 percent of IQ scores fall within the normal range. Note, however, that this is a norm-referenced test. In fact, actual IQ scores have risen in many nations; 100 is no longer exactly the midpoint. Furthermore, in practice, scores below 50 are slightly more frequent than indicated by the normal curve shown here because severe disability is not the result of normal distribution, but of genetic and prenatal factors.