On Tue, Apr 25, 2017 at 07:39:45AM +0000, Hulliger Beat wrote:
Last week a student asked me whether he should eliminate the intercept in
a simple linear regression when it is not significantly different from 0. Yes,
I said: It is very simple to remove it in PSPP. How wrong was I! There is no
option /NOORIGIN in the PSPP Regression procedure.
I have seen the discussions about this issue and the corresponding
proposals. I tried GLM but no coefficients are output. I tried with dummies but
a bit of algebra convinced me that this does not work. I thought the simplest
thing is to delete the column of ones in the design matrix. I have downloaded
the code and looked into linreg.c. Of course, things are a bit more complicated
than it seems at first. Say, my knowledge of C is not enough to venture into
the code.
So back to crude SPSS-Syntax for simple linear regression (say a ratio
model): See the code below.
It would be nice to have a /noorigin option in the Regression procedure!
I have pushed a change impementing the /origin and /noorigin options.
/noorigin (ie. the intercept is included in the model) is the default.
Right now I have given it only a few rudimentary tests, so - as always - caveat
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