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

n**Variation **(SS)** **= Sum of
Squares

n**Variance** (s2 or S2) = SS/N (deviation scores squared/N)

n**Standard 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** Ð then scores were very close together