Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
From | George Murray <george.murray16@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: Computing the proportion of significant variables after running numerous regressions |
Date | Mon, 14 May 2012 18:30:10 +1000 |
Phil, Thank you so much for your help, this worked perfectly. I have one more query, however. I also need a vector of the bias-corrected confidence intervals (which can be obtained with the -estat bootstrap- command). I replace two of the commands you suggested with these two commands as follows: -postfile `postfile' foreign _b_cons _se_cons _ci_bc_cons _b_mpg _se_mpg using "`results'"- .............(all I did was add "_ci_bc_cons") -post `postfile' (`level') (_b[_cons]) (_se[_cons]) (_ci_bc[_cons]) (_b[mpg]) (_se[mpg])- .............(all I did was add "(_ci_bc[_cons])") and I also wrote -estat boostrap- after the bootstrap, rep(10)... command However, I get the following error: _ci_bc not found post: above message corresponds to expression 3, variable _ci_bc_cons r(111); Does anyone know how to solve this problem? Thanks in advance, George. On Mon, May 14, 2012 at 12:05 AM, Phil Clayton <philclayton@internode.on.net> wrote: > George, > > There are various ways to do this. One is to use -post- after each bootstrapped regression to store the results of that regression in a "results" dataset, similar to a Monte Carlo simulation. You can then access the results dataset and manipulate it however you like. > > Here's a basic example that uses the auto dataset and loops over the levels of "foreign" (ie 0 and 1), runs a bootstrapped regression of price on mpg for each level, and displays the resulting coefficients and standard errors. > > --------- begin example --------- > * load dataset > sysuse auto, clear > > * set up temporary file for results > tempfile results > tempname postfile > postfile `postfile' foreign _b_cons _se_cons _b_mpg _se_mpg using "`results'" > > * run bootstrapped regression for each level of foreign > set seed 1 // so that you can repeat your analysis > levelsof foreign, local(levels) > foreach level of local levels { > bootstrap, rep(10): regress price mpg if foreign==`level' > post `postfile' (`level') (_b[_cons]) (_se[_cons]) (_b[mpg]) (_se[mpg]) > } > postclose `postfile' > > * display results > use "`results'", clear > list > --------- end example --------- > > Since you're running ~1000 models you may wish to change "foreach" to "qui foreach", and monitor the iterations using the _dots command (see Harrison DA. Stata tip 41: Monitoring loop iterations. Stata Journal 2007;7(1):140, available at http://www.stata-journal.com/article.html?article=pr0030) > > Phil > > > On 13/05/2012, at 10:06 PM, George Murray wrote: > >> Dear Statalist, >> >> I am using the -foreach- command to run approximately 1000 >> (bootstrapped) regression models, however I require an efficient way >> of calculating the proportion of the regression models which have a >> statistically significant constant at the 5% level; and of the >> constants which are statistically significant, the proportion which >> are positive. Below each of the 1000 regressions I run, a table is >> displayed with the following format: >> >> --------------------------------------------------------------------------------------------------- >> | Observed Bootstrap >> V0 | Coef. Bias Std. Err. >> [95% Conf. Interval] >> -------------+------------------------------------------------------------------------------------ >> V1 | .00968169 -.0000537 .00057051 .008721 .0111218 (BC) >> V2 | -.00110469 .0000782 .000691 -.0023101 .000459 (BC) >> V3 | .00468313 -.0001562 .00084971 .0031954 .0064538 (BC) >> _cons | -.00076976 .0001811 .00176677 -.0044496 .0025584 (BC) >> -------------------------------------------------------------------------------------------------- >> >> I would be *very* grateful if someone knew the commands which would >> allow me calculate this. In the past, I have used (a highly tedious >> and embarrassing approach on) Excel where I filtered every Nth row, >> and wrote a command to display 1 if the coefficient lies within the >> confidence interval, and 0 if not. This time, however, I am running >> numerous models and require a quicker approach. >> >> One more question -- is there a way to create a new variable where the >> coefficients of V1 (for example) are saved, so I can calculate the >> mean, standard deviation etc.of V1? >> >> If someone could answer at least one of these two questions, it would >> be very much appreciated. >> >> George Murray. >> * >> * For searches and help try: >> * http://www.stata.com/help.cgi?search >> * http://www.stata.com/support/statalist/faq >> * http://www.ats.ucla.edu/stat/stata/ > > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/