Nominal scale: variables have no numerical, quantitative properties; most independent variables are nominal. Ordinal scale: minimal quantitative distinctions; can rank order the levels of a variable; intervals between each scale probably aren"t equal. Interval scale: much more detailed quantitative properties; intervals between the next levels are equal in size; generally have five or more quantitative levels; no absolute zero point. Ratio scale: much more detailed quantitative properties; variables have both equal intervals and an absolute zero point that indicates absence of the variable being measured. Describing results: comparing group percentages, correlating scores of individuals on two variables, comparing group means. Central tendency: mean (average score); median (score that divides group in half); mode (most frequent score). Variability: range (minimum and maximum score); standard deviation (average deviation from mean); variance (mean of squared deviations). Modality: number of peaks in the distribution.