Methods
2.3.1. Principle component analysis (PCA)
Essentially, PCA maximizes the correlation between the original
variables to form new variables that are mutually orthogonal, or
uncorrelated (Abdul-Wahab et al., 2005). PCA has the ability to
reduce a large amount of data to a new set of variables (principle
components, PCs) where the number of principal components is
less than or equal to the number of original variables, which gives
the linear combination of the original set of data. After variable
reduction in the data set, PCA allows the identification and observation
of the source of variation. PCA is generally written as: