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From |
Maarten Buis <maartenlbuis@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: Fw: st: xtfmb: Fama MacBeth regression |

Date |
Tue, 17 Jul 2012 10:24:49 +0200 |

On Tue, Jul 17, 2012 at 9:10 AM, <biljana.dlab@bf.uzh.ch> wrote: > I would like to do Fama MacBeth regression and i used xtfmb function. > > however I would like now to do it step-by-step, for each year I have in > sample (1971 - 2001), so that I see changes from one year to the next one, > later on I can take the average of the coefficients: > > so I tried with this code: > > > forvalues fyear ‘ i ’ { > reg Cash Debt > matrix coefficient =e(b) > matrix regression_result [ ‘ i ’, 1] =coefficient [1 ,1] > matrix regression_result [ ‘ i ’, 2] =coefficient [1 ,2] > matrix regression_result [ ‘ i ’, 3] = e(N) > matrix regression_result [ ‘ i ’, 4] = e(r2_a) > i = ‘ i ’ +1 > } > matrix list regression_result > > however I am getting error message A couple of comments: First, if you are referring to user written software (in this case -xtfmb-) you need to tell us where you got it from (SSC, SJ, some private website, ...). The logic behind this requirement is that often there are multiple versions of user written software floating around in cyberspace and you can imagine that not talking about the same program can lead to a lot of unnecessary confusion. This is clearly explained in the Statalist FAQ, which you were asked to read before posting on Statalist. The Statalist FAQ also asked you to say exactly what Stata told you in return, not just that it gave you an error message, but also which error message. Second, I see a couple of problems with your loop. First, you seem to mixing the syntaxes of -while- and -forvalues-, or looping syntaxes from different programming languages. For the right syntax see -help forvalues-. In this case I would either use a combination of -levelsof- and -foreach- or -forvalues-. The latter is a bit more fragile as it would break when you get the beginning or end year wrong or if there are gaps. Second, you are not using the right single quotes for referencing local macros, see -help macro-. It is a bit hard to explain which quotes are the right ones as their location on the keyboard can differ quite a bit from country to country. On German keyboards the opening quote is above the ue (in combination with the shift key), the closing quote is right of ae (also in combination with the shift key)(*). Third, you are not estimating the regression on different sub-samples, but just repeat the same regression on the entire population over and over again. Third, there is an easier solution that does not require you to write a loop: -statsby-. Below is an example that illustrates -levelsof- and -foreach-, -forvalues- and -statsby-: *--------------------- begin example ------------------------ sysuse nlsw88, clear //------------------------------- doing the loop with foreach // create an empty matrix that is to be filled in matrix regression_results = J(13, 5, .) matrix colnames regression_results = age grade _cons N r2_a // collect the values of age in local levs levelsof age, local(levs) // loop over those values local j = 1 foreach i of local levs { reg wage grade if age == `i' matrix regression_results[`j',1] = `i', e(b),e(N),e(r2_a) local j = `j' + 1 } // display the result matlist regression_results //------------------------------ doing the loop with levelsof local j = 1 forvalues i = 34/46 { reg wage grade if age == `i' matrix regression_results[`j',1] = `i', e(b),e(N),e(r2_a) local j = `j' + 1 } // display the result matlist regression_results //-------------------------------------- the easy alternative statsby _b e(N) e(r2_a), by(age) : reg wage grade list *---------------------- end example ------------------------- (For more on examples I sent to the Statalist see: http://www.maartenbuis.nl/example_faq ) Hope this helps, Maarten (*) For those not familiar with German: ue and ae are the plain text equivalents of u umlaut or u with two dots on top and a umlaut or a with two dots on top, and they are used so often in German that they are directly on the German keyboard. -------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://www.maartenbuis.nl -------------------------- * * 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/

**Follow-Ups**:**Antwort: Re: Fw: st: xtfmb: Fama MacBeth regression***From:*biljana.dlab@bf.uzh.ch

**Antwort: Re: Fw: st: xtfmb: Fama MacBeth regression***From:*biljana.dlab@bf.uzh.ch

**References**:**Fw: st: xtfmb: Fama MacBeth regression***From:*biljana.dlab@bf.uzh.ch

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