Steve Simon <[EMAIL PROTECTED]> wrote:
>I'm helping out someone taking a Statistics class and her instructor is
>drawing a distinction between "part correlation" and "partial correlation".
>I had never heard of the term "part correlation" before.
>
>As best I understand it, If you have three variables, A, B, C, then you can
>compute residuals for A (call it A-A') for a regression model using A as the
>dependent variable and C as the independent variable. You can also compute
>the residuals for B (call it B-B') using B as the dependent variable and C
>as the independent variable.
>
>The definition of partial correlation between A and B adjusting for C is the
>correlations between (A-A') and (B-B'). The definition of part correlation
>between A and B adjusting for C is the correlation between (A-A') and B.
>
>The instructor claims that the part correlation is usually better (more
>interpretable?) but that SPSS and other software will not compute such a
>correlation.
>
>Does any of this make sense? Why would you ever want to use a part
>correlation?
>
Steve,
many other comments have been posted, and from my perspective most were
reasonable. If you want a reasonably clear discussion of these distinctions,
check out the Cohen and Cohen book (Applied Multiple Correlation / Regression,
I think). They refer to the part correlation as a semi-partial correlation.
Hope this helps,
Dan Nordlund
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