PSY 241 Lecture Notes - Lecture 4: Sample Size Determination, Statistical Parameter, Squared Deviations From The Mean
20 Sep 2016
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Document Summary
Provides a quantitative measure of the degree to which scores in a distribution are spread out or clustered together. Measures how well an individual score (like central tendency) represents a distribution. Provides information about how much error to expect when using a sample to represent a population. Distance between the largest score and the smallest score in the distribution. Upper real limit of the highest score minus the lower real limit of the lowest score. Range= url highest x lrl lowest x. Does not consider all the scores in the distribution. Quartiles divide distribution into 4 equal parts: 1st quartile= lowest 25, 2nd quartile= 50% of scores below the median, 3rd quartile= 75% of scores below. Interquartile range is the distance between the 1st quartile and the 3rd quartile: leaves out the top and bottom 25, q3-q1. Most commonly used and most important measure of variability. Approximates the average distance between each score and the mean.
