Dear all, I found pls.pcr package will give different results if the data are centered and scaled using scale(). I am not sure about when I should scale my data, and whether the dependent variable should be scaled. If the dependent variable is scaled, how I give a prediction to the real data? I appreciate for any suggestions and comments. Best regards, Jinsong ===== (Mr.) Jinsong Zhao Ph.D. Candidate School of the Environment Nanjing University 22 Hankou Road, Nanjing 210093 P.R. China E-mail: jinsong_zh at yahoo.com
center or scale before analyzing using pls.pcr
2 messages · Jinsong Zhao, Bjørn-Helge Mevik
Jinsong Zhao <jinsong_zh at yahoo.com> writes:
I found pls.pcr package will give different results if the data are centered and scaled using scale().
Centering is done automatically by all implementations of PLSR I am aware of (including pls.pcr, afaics).
I am not sure about when I should scale my data,
There are no fixed rules about this. Many practitioners live more or less by the rule that unless the variables are `of the same type' or have equal or comparable scales, they are scaled. One example of data that is typically not scaled (at least to begin with) is spectroscopic data.
and whether the dependent variable should be scaled.
There is no need for scaling the dependent variable.
Bj?rn-Helge Mevik