Re: PSPP Regression with /noorigin

[John Darrington]

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 
emptor!

J'


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