Indicate the relative position of an individual in a group. The percentage of the group that scored below a given score. Express test standards, or norm, in percentile ranks in multiples of 5. Determine test score (percentile) that corresponds to each rank. Mean, median and mode are at the same point (center) 68% of scores within + one sd. 99% of scores are within + three sds. Provide a common unit of measurement across different tests. Translate each score into a standard score. Z18 = (18 12)/4= (6/4) = 1. 50. 18 is 1. 50 standard deviations above the mean. Z 9 = (9-12)/4 = (-3/4) = -. 75. T 18 = [10 (18-12)/4 ] + 50. T 18 is 65, which is 1. 5 standard deviations above the mean. T 9 is 42. 5, which equals . 75 sd below the. Write the formula in a spread sheet.
