Compare the standardized and unstandardized 2D PCA results. Consider both the variance percentages and the class colours.
Someone concludes: "The unstandardized representation is necessarily better for this assignment because it retains almost 100%." Which response is best justified?

Question

Compare the standardized and unstandardized 2D PCA results. Consider both the variance percentages and the class colours. 
 Someone concludes:  "The unstandardized representation is necessarily better for this assignment because it retains almost 100%."  Which response is best justified?

Accepted Answer

The conclusion does not follow: scaling changes the variance being represented and the relative influence of features, so the percentages alone cannot rank usefulness.

Answer

Correct: each percentage measures diagnosis accuracy, so the larger value is always preferable.

Answer

Incorrect: standardisation always produces more separated diagnosis groups, whatever the data.

Answer

Correct: units can change axis labels but cannot influence which principal directions are selected.

Crowdly

Compare the standardized and unstandardized 2D PCA results. Consider both the va...

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