PSYC 241 Lecture Notes - Lecture 4: Variance, Squared Deviations From The Mean, Statistical Inference
Document Summary
A measure of how spread out the scores are in distribution. Accompanies central tendency as basic descriptive statistic. Central tendency = central point of distribution. Variability = how scores are scattered around central point. Central tendency and variability are the two primary values used to describe a distribution of scores. An important component of most inferential statistics. Measures degree of which scores are spread out or clustered together. Provides a measure of how accurately any individual score or sample represents entire population. When population variability is small, all of scores are clustered close together. Any individual score or sample will provide a good representation of the entire set. When variability is large and scores are widely spread, one or two extreme scores can give distorted picture of general population. Standard distance between a score and the mean. Preferable to range, because range is based on most extreme scores. Compute the deviation (distance from the mean) for each score.
