Statistics 4 Variance

Measures of Central Tendency

nAlways report a measure of central tendency (Mean & SD) and a measure of variability to describe a set of scores

nVariation (SS) = Sum of Squares

nVariance (s2 or S2) = SS/N (deviation scores squared/N)

nStandard deviation (s or SD) = square root of variance

nMeasures of variability provide a quantitative measure of the degree to which scores in a distribution are spread out or clustered together on the scale.

nIf variance = 0 then all scores are the same, NO variability exists

nIf variance is large - then scores were very far apart

nIf variance is small – then scores were very close together