1. Calculating Standard Deviation (sample)
s=
∑( Xi − X ) 2 SS
n −1
Step 1: Calculate Sum of Squares
SS = ΣX2 – (ΣX)2 /N
Square each score and then add Add up all the scores, square the
up all the squared scores sum, divide by the sample size
Step 2: Plug in SS (what you got above) into the numerator of the
standard deviation formula
s = √ SS
n–1
Step 3: Interpretation (On average, observations in the sample are (insert standard
deviation) units away from the sample mean of (insert mean).