PSYC 210 Chapter Notes - Chapter 5: Linear Map, Standard Deviation, Conditional Probability
24 Mar 2013
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Document Summary
Chapter 5 measures of variability (p. 75) Variability / dispersion the degree to which individual data points are distributed around the mean. Range (r) the distance from the lowest to the highest score. R = highest number lowest number. Interquartile range the range of the middle 50% of the observations. If it discards too much data then it is not a very good estimate of the overall variability. Discards the lower and upper 25% of the distribution. Trimmed samples samples with a percentage of the extreme scores removed. Trimmed statistics statistics calculated on trimmed samples. The average of the absolute values of the deviations from the mean. Sample variance (s2) sum of the squared deviations about the mean divided by n 1. Population variance ( 2) variance of a population; usually an estimate, rarely computed. Standard deviation (sd, s or ) the square root of the variance.
