I have several variables that I included in a PCA: body length, mass, and development stage.
We often calculate a variable we call 'condition'm which is the residuals of mass ~ (body length)^3.
My boss asked me to also do a PCA including condition, body length, and development stage. Including both condition and body length seems odd to me, since body length is used in the calculation of condition, as described above. Is there a potential for some kind of artefact or other statistical problem with including both condition and body length in the PCA?