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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
RE: st: using different macros everytime |

Date |
Mon, 16 Jun 2008 16:31:55 +0100 |

You don't need to convince me. You need to convince yourself which way is better. As you say, doing other things inside the loop makes looping a more natural approach to coding. Shehzad Ali Thanks, Nick. This works perfectly well. I take your point that if I was just running a treatreg model then there wasn't much point in doing it this way. But I am actually running a long list of commands within the forval loop for each set of macros, i.e. I run treatreg using one set of macros followed by equity analysis based on predictions from treatreg (all within the same loop), and then I run the same analysis using a different set of macros. I am not sure if you are convinced that this is the best way of doing it. But your advice is always very helpful and I would appreciate any suggestions to improve my Stata practice. Nick Cox Going back to your original example: local xset `" "x1 x2" "x1 x2 x3" "' local zset `" "x1 x2 v1" "x1 x2 x3 v1" "' * start of stuff for program or do file only local Tx : word count `xset' local Tz : word count `zset' if `Tx' != `Tz' { di as err "no go; numbers of x sets and z sets do not match" exit 498 } * end of stuff for program or do file only forval t = 1/`T' { local x : word `t' of `xset' local z : word `t' of `zset' treatreg y1 `x', treat(y2 = `z') } I can't see much advantage in doing it this way unless the number of sets is much larger than in the example. Nick n.j.cox@durham.ac.uk Shehzad Ali Your solution makes good sense. With apologies, can I ask for a simple clarification here? I didn't completely understand - forval - loop part of the solution. I understand that we define local T which captures no. of sets and then forval loops each one of them one after another but I am not sure how I use my treatreg commands (say for instance I only wanted to run a simple treatreg command). Nick Cox On the major point, you can bind variable names into groups using double quotes " ". This follows from the syntax that double quotes bind more tightly than spaces separate. Thus you could go local xset `" "a b c" "d e f" "g h j" "' local zset `" "A B C" "D E F" "G H J" "' Note the use of compound double quotes in defining the whole. Then local T : word count `xset' forval t = 1/`T' { [stuff referring to word `t' of `xset'] [stuff referring to word `t' of `zset'] } I'm all for improving one's mastery of Stata technique, but sometimes it's just quicker to crunch through the variations of commands using a do file and a decent text editor -- especially if you may spend much time later trying to work out what was that clever thing you did. Incidentally, the approach here of replacing variables by their means and then reinstating them is quite unnecessary and indeed I would classify it as very bad style. Never touch originals you care about. Rather -generate- new variables with the means concerned. Or, something more like this: gen work1 = . gen work2 = . within a loop { su <something>, meanonly replace work1 = r(mean) su <otherthing>, meanonly replace work2 = r(mean) } Shehzad Ali Let me write down a few details about the analysis I am trying to run. Please ignore if some of the details are irrelevant. I am trying to run what they call 'standardisation' in literature. So here is what I intend to do. First loop: 1. run treatreg model: treatreg y1 x1 x2 x3 x4 x5, treat(y2=x1 x2 x3 x4 x5 instrument1) 2. then set x1 x2 at their mean values (first generate copies of x1 x2, i.e. x1_copy x2_copy, then summarize original x1 x2 and replace them with their mean values). 3.then predict yhat (so basically it uses coefficients from treatreg but x1 x2 are at their mean values and others at their actual values) 4. drop x1 x2 (which were set at their mean values) and then rename x1_copy and x2_copy as x1 x2 (so these variables are back as original) Second loop: 4. Run the same as above but this time setting x2 x4 x5 at their mean values Going on further, I have a few more loops where the variables which are set to their mean values are different (no pattern of selection of variables) What I was thinking of doing was to define sets of macros, i.e. for first loop, define macro1 as variables to be set at their mean value and macro2 as variables to be left as original. For second loop, I do the same and it goes on until I have run all the loops I wanted to run. What I needed help with is how to assign names to each macro and then I can run a foreach loop so that the macros are defined at the start and then treatreg and the rest is run as a loop several times. Maarten buis It is usually better practice to work with locals. Anyhow the answer to your question depends on the kind of pattern you want those models to follow. Do you want something like x1 x2 x3 x1 x2 x4 x1 x2 x5 or x1 x2 x3 x1 x2 x3 x4 x1 x2 x3 x4 x5 or all combinations. Moreover, do these variables have such systematic names, or do they have more meaningful, but less systematic names? Shehzad Ali > Sorry, Martin, it was a mistake. I actually meant global. The models > I am > currently using are: > > * First model: > > global xvar "x1 x2" > > global zvar "x1 x2 v1" > > treatreg y1 $xvars, treat(y2=$zvars) > > * Second model: > > global xvar "x2 x3 x4" > > global zvar "x2 x3 x4 v1" > > treatreg y1 $xvars, treat(y2=$zvars) > > Note that I am not just adding one or two additional variables in the > second > model, but I am actually using a different set of variables the > second time. > Now I want to loop this somehow so that I just write the - treatreg - > command line once and - foreach - can pick up different sets of > macros each > time the loop is run. Can you please suggest the best way to do it? Martin Weiss > Just a remark: are you sure you want to reference a -local- with the > $ > sign? I do not think that this will actually work... Shehzad Ali > > I want to run a 2 separate treatreg models with the same y var but > > different set of x vars. Here is what I am doing: > > > > * First model: > > > > local xvar "x1 x2" local zvar "x1 x2 v1" > > > > treatreg y1 $xvars, treat(y2=$zvars) > > > > * Second model: > > > > local xvar "x1 x2 x3" local zvar "x1 x2 x3 v1" > > > > treatreg y1 $xvars, treat(y2=$zvars) > > > > Now I want to loop this somehow so that I just write the - treatreg > - > > line once but - foreach - can pick up different sets of macros. Can > you > > suggest the best way to do it? * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**RE: st: using different macros everytime***From:*"Shehzad Ali" <sia500@york.ac.uk>

**RE: st: using different macros everytime***From:*Maarten buis <maartenbuis@yahoo.co.uk>

**RE: st: using different macros everytime***From:*"Shehzad Ali" <sia500@york.ac.uk>

**RE: st: using different macros everytime***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**RE: st: using different macros everytime***From:*"Shehzad Ali" <sia500@york.ac.uk>

**RE: st: using different macros everytime***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**RE: st: using different macros everytime***From:*"Shehzad Ali" <sia500@york.ac.uk>

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