Choosing the right number of principal components

Machine Learning for Marketing Analytics in R

Verena Pflieger

Data Scientist at INWT Statistics

No. relevant components: explained variance

# Proportion of variance explained:
summary(pcaCust)

Importance of components:
                          PC1    PC2    PC3     PC4     PC5     PC6     PC7
Standard deviation     2.0951 1.8379 1.2960 1.20415 1.12301 1.07453 0.80486
Proportion of Variance 0.2743 0.2111 0.1050 0.09062 0.07882 0.07216 0.04049
Cumulative Proportion  0.2743 0.4855 0.5904 0.68106 0.75989 0.83205 0.87254
                           PC8     PC9    PC10    PC11    PC12    PC13
Standard deviation     0.78236 0.72452 0.61302 0.48428 0.36803 0.25901
Proportion of Variance 0.03826 0.03281 0.02349 0.01466 0.00847 0.00419
Cumulative Proportion  0.91079 0.94360 0.96709 0.98175 0.99021 0.99440
                          PC14    PC15    PC16
Standard deviation     0.20699 0.17126 0.13170
Proportion of Variance 0.00268 0.00183 0.00108
Cumulative Proportion  0.99708 0.99892 1.00000

No. relevant components: Kaiser-Guttman criterion

Kaiser-Guttman criterion: Eigenvalue > 1

pcaCust$sdev ^ 2

 [1] 4.38961593 3.37778445 1.67965616 1.44997580 1.26115351 1.15461579
 [7] 0.64780486 0.61209376 0.52492468 0.37579685 0.23452736 0.13544710
[13] 0.06708362 0.04284504 0.02933027 0.01734481

No. relevant components: screeplot

The screeplot or: "Find the elbow"

screeplot(pcaCust, type = "lines")
box()
abline(h = 1, lty = 2)

Suggested number of components by criterion

Explained Variance	Kaiser-Guttman	Screeplot
5	6	6

The biplot

biplot(pcaCust, choices = 1:2, cex = 0.7)

Hands on!

Machine Learning for Marketing Analytics in R