. Consider the p = 4 process variables in Table 10-6. After applying the PCA pro-

cedure to the first 20 observations data

(see Table 10-7), suppose that the first three principal components are retained.

(a) Obtain the principal component scores. (Hint: Remember that you must work in standardized Vari-
ables.)

(b) Construct an appropriate set of pair-
wise plots of the principal compo-
nent scores.

(e) Calculate the principal component scores for the last 10 observations.
Plot the scores on the charts from part

(b) and interpret the results.