st: RE: looping a regression, exporting the graphs

[Nick Cox <n.j.cox@durham.ac.uk>]

This is legal code: 

foreach y of varlist Early1-Late3a {
xi: logit `y' i.eth2 age i.invsurg2 i.region i.dep if dep!=9 & sex==2 & ICD10=="C50", or

	
qui graph export "T:\Test\Early1_UK_`y'.png", replace	
}

assuming that the gap generates a graph for that variable. You'd need to pass the text "`y'" to the do-file as a an argument. _The do-file cannot see your local macro; it can only receive it as an argument._ 

The help and documentation for -foreach- are a little thin unless you know the command already. There are longer-winded tutorials at 

SJ-3-2  pr0009  . . . . . . . . . . . . . Speaking Stata:  Problems with lists
        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N. J. Cox
        Q2/03   SJ 3(2):185--202                                 (no commands)
        discusses ways of working through lists held in macros

SJ-2-2  pr0005  . . . . . .  Speaking Stata:  How to face lists with fortitude
        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N. J. Cox
        Q2/02   SJ 2(2):202--222                                 (no commands)
        demonstrates the usefulness of for, foreach, forvalues, and
        local macros for interactive (non programming) tasks

-- especially 2(2): 202-222 (2002) (I didn't fix that; it just fell out that way....) 

As these articles are >> 3 years old, .pdf copies are freely available and available for free at www.stata-journal.com 

. search foreach, sj 

will give clickable pointers. 

Nick 
n.j.cox@durham.ac.uk 

Tim Evans

I am running a number of logistic regression models (Stata 11.2, Windows XP) and then exporting a graph out of each regression using the following as dependant variables:

Early1
Early2
Early1a
Early2a
Late1
Late2
Late3
Late1a
Late2a
Late3a

Each model is run twice, once for the whole dataset and once for a sub-sample, giving me 20 regression commands

The trouble with this is I have a lot of code and its tricky keeping a check of it when I change something in one model that I want to run in later models. I've already stripped out my graph formatting into a separate do file for this purpose.

What I want to know is, is there a way I can bundle up my dependant variables in a loop or similar and then have one regression command that loops around? Crucially to this, is that I also need the graphs that I am labelling to match up to the regression I have run - so some reference to a macro containing the definition (i.e. the name of the dependant variable, along with whether it is for England or UK.

Would I use something like:?

foreach varname of varlist Early1-Late3a {
xi: logit XXX i.eth2 age i.invsurg2 i.region i.dep if dep!=9 & sex==2 & ICD10=="C50", or
	
qui do "T:\Test\labelling" "O/R of early detection (Early1_UK)"
qui graph export "T:\Test\Early1_UK.png", replace	
}

I'm not sure how I would treat the dependant variables in the loop, or how to get the labelling and export to work though or the exporting graph with a new name for each graph.


My models are thus (I've only pasted 2 of the 20!):

***BEGIN***

***EARLY1 Analysis

preserve
xi: logit Early1 i.eth2 age i.invsurg2 i.region i.dep if dep!=9 & sex==2 & ICD10=="C50", or
	
qui do "T:\Test\labelling" "O/R of early detection (Early1_UK)"
qui graph export "T:\Test\Early1_UK.png", replace
restore

I then run this again, but I'm only interested in a sub-sample of the above

preserve
xi: logit Early1 i.eth2 age i.invsurg2 i.region i.dep i.screening2 if dep!=9 & sex==2 & ICD10=="C50" /*
*/			 & !inlist(region, 2, 7, 11) & NEW==2, or

qui do "T:\Test\labelling" "O/R of early detection (Early1_England)"
qui graph export "T:\Test\Early1_England_screening.png", replace
restore

***EARLY2 Analysis

preserve
xi: logit Early2 i.eth2 age i.invsurg2 i.region i.dep if dep!=9 & sex==2 & ICD10=="C50", or
	
qui do "T:\Test\labelling" "O/R of early detection (Early2_UK)"
qui graph export "T:\Test\Early2_UK.png", replace
restore

I then run this again, but I'm only interested in a sub-sample of the above

preserve
xi: logit Early2 i.eth2 age i.invsurg2 i.region i.dep i.screening2 if dep!=9 & sex==2 & ICD10=="C50" /*
*/			 & !inlist(region, 2, 7, 11) & NEW==2, or

qui do "T:\Test\labelling" "O/R of early detection (Early2_England)"
qui graph export "T:\Test\Early2_England_screening.png", replace
restore

AND SO ON.

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