n**Variables and individual scores**

nCapital letters, (X, Y) indicate variables

nThe score for subject 4 would be written X4

n**Sums**

nThe upper case Greek sigma to indicate "the sum
of"

nLower case **n** for the __number__ of subjects in a __sample__

nUpper case N for the __number__ of subjects in __population__

n**Raw data** __X____1____ X____2____ X____3____ X____4__

3 5 1 2

Note: the sample size is n = 4