PSYC 204 Lecture 6: PSYC STATS 6
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Topic 4 = descriptive statistics - measures of the spread of the data. Variation = degree of which scores differ from one anotheror from central tendency [mean] Disadvantage = sensitive to sample size & data. Variation = distance between each scores & mean. So mean of squared deviation scores = (cid:2779) Take into account all scores & how differ from mean. But sum of deviation scores x = 0 so use sum of squared deviations scores x2 for (+) value. Ex: {-3, 0, 9, 10} more scattered than {1, 2, 8, 5} {-3, 0, 9, 10} - x = 4 (cid:2779) = (cid:2781)(cid:2786)+(cid:2778)(cid:2783)+(cid:2779)(cid:2782)+(cid:2780)(cid:2783) {1, 2, 8, 5} - x = 4 (cid:2779) = (cid:2786)+(cid:2781)+(cid:2778)(cid:2783)+(cid:2778) (cid:2872) Use sample to deduce variance from population so not interesting in sample size but want larger. Variance = mean of squared deviation scores *mean square: for population np. *if know entire population: for sample *biased, for sample representing.
