Hi,
Not sure if it's appropriate to ask this here but hope someone can give me some hints.
I'm a beginner in PCA and I know that mostly we should centered our data before analyzing score matrix and loading matrix. Say the raw data are from 3 samples (s1,s2,s3) and have 2 variables (v1, v2).
(1).
If the raw data are:
for s1: v1=1; v2=101
for s2: v1=2; v2=102
for s3: v1=3; v2=103
(2).
After centering, the data should be:
for s1: v1=-1; v2=-1
for s2: v1=0; v2=0
for s3: v1=1; v2=1
Since, for both v1 and v2, the variance is 2/3 in both (1) and (2), why do we need to center the data?
Thank you so much.
Mark
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