Provides an estimate of the typical, usual, or normal score found in a distribution of raw scores. Sum of all scores in a distribution divided by the number of scores observed (i. e. , the sample size: median. For an ordinal or interval/ratio variable, the middle score in a ranked distribution, the score for which half of all cases fall above and half fall below: mode. The most frequently occurring score in a distribution: measuring spread. Subtract the mean from each score: (x mean); scores above the mean produce positive deviation scores, while scores below the mean produce negative deviation scores: variation or sum of squares. (x mean); should equal 0: variance (sx, [average variation of scores in a distribution] Describes how scores of an interval/ratio variable are spread across the distribution in relation to the mean score; Divide by n 1 (adjustment for sample size and sampling error): standard deviation (sx) Take the square root of the variance.