Distributions of scores are evaluated with respect to their central tendency and variability. Three measures of central tendency discussed in Chapter 10 were the mean, median, and mode. Two measures of dispersion treated were Range and Standard Deviation. Individually, the different procedures have advantages and disadvantages in particular situations. They should therefore be chosen with the problem context in mind.

Shapes of distributions can be described in terms of their variability, symmetry, modality, skewness, and kurtosis. Graphing of frequency distributions facilitates visual interpretation of group performance. The chapter demonstrated three procedures for plotting frequency distributions: Frequency Polygon, Histogram and the Ogive. The properties of the normal distribution were presented with applications in deriving percentile ranks.

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