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Feature Transformation Techniques

Logarithmic transformation

  • Use the logarithmic operation to compress the range of values and reduce skewness
  • Log is essentially finding what the power is needed for the base to obtain the input
  • Base 2: log2(X)=Ylog_2(X)=Y is finding what should YY be such that 2Y=X2^Y=X, so log2(8)=3log_2(8)=3 because 23=82^3=8
  • Base 10: log10(X)=Ylog_{10}(X)=Y is finding what should YY be such that 10Y=X10^Y=X
  • Base e or natural log: ln(X)=Yln(X)=Y is finding what Y be such that eY=Xe^Y=X

Square Root Transformation

  • This technique reduces the range of values by taking the square root of each value. It is useful for stabilizing variance.

Box-Cox Transformation

  • A family of power transformation