**Edit: 8 Aug. Remarks added in “Regressions with no constant term”.**

## introduction

It would be fair to say that this post is primarily for my reference, but it does provide a second example of looking at all subsets of multicollinear data.

As we originally did for the raw data, so for the standardized data: we looked at multicollinearity for the three regressions of most interest – namely, the best 2- and 3-variable regressions, and the all-4-variable regression.

Now, as we did for the raw data, so for the standardized data: let’s look at all subsets (of columns) of the design matrix X. (In fact, it is easier to look at the equivalent: all subsets of rows of the transpose of the design matrix, X’.

Nevertheless, let me summarize what we will find. You may not feel a need to look at the computations. I think at the very least you will want to look at the section on regressions without a constant term, and at the 3-variable subsets.

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