The base line in Figure 6B is the same as in Figure 6A, but the vertical axis indicates the number of exams receiving each score. The frequency polygon is constructed by simply connecting the tops of the columns of x's. The shape of the graphs in Figure 6 suggests a very important psychological fact. This picture is typical of human traits. People are not easily categorized as bright or stupid, or as anxious or calm.
Most individuals fall somewhere in between.
Two forms of frequency distribution. Such figures are seldom used because they are tedious to construct. Figure B is a frequency polygon of the same data. All frequency polygons constructed from real measurements will show some unevenness. In general, the more measurements we take, the smoother the graph becomes, because many of the irregularities are the result of chance variations in the population measured.