Preface to First Edition - lib

294 PRINCIPAL COMPONENT ANALYSISR> plot(heptathlon_pca)heptathlon_pcaVariances0 1 2 3 4Figure 16.3Barplot of the variances explained by the principal components.(with observations for PNG removed).The correlation between the score given to each athlete by the standardscoring system used for the heptathlon and the first principal component scorecan be found fromR> cor(heptathlon$score, heptathlon_pca$x[,1])[1] -0.9931168This implies that the first principal component is in good agreement with thescore assigned to the athletes by official Olympic rules; a scatterplot of theofficial score and the first principal component is given in Figure 16.5.© 2010 by Taylor and Francis Group, LLC