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From |
Chris Witte <eljefespeaks@yahoo.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Re: using coefficients from model |

Date |
Mon, 30 Mar 2009 13:13:09 -0700 (PDT) |

thanks a million Martin!... Now if I only had the last few hours back. ----- Original Message ---- From: Martin Weiss <martin.weiss1@gmx.de> To: statalist@hsphsun2.harvard.edu Sent: Monday, March 30, 2009 3:00:34 PM Subject: st: Re: using coefficients from model <> ***** sysuse auto, clear reg price weight rep tr g y=_b[_cons]+_b[weight]*weight+_b[rep78]*rep+_b[trunk]*trunk *compare to built-in solution predict pred compare pred y ***** HTH Martin _______________________ ----- Original Message ----- From: "Chris Witte" <eljefespeaks@yahoo.com> To: <statalist@hsphsun2.harvard.edu> Sent: Monday, March 30, 2009 9:55 PM Subject: st: using coefficients from model > I am using stata 9.2. I would like to know how to call the coefficients from the estimation results matrix e(b) and use them in an equation. For example, if my matrix e(b) has values for "_cons" and coefficient "test", I would like to calculate the answer to an equation y = [_cons] + x*[test]. How can I do this? > > The reason why I want to do this is because I am trying to find the value _fracpoly_ adjusts its estimates by. If I use this output from my _fracpoly_ estimation: > > study1twsg Coef. Std. Err. t P>t [95% Conf. Interval] > Itemp__1 15093.12 4454.121 3.39 0.012 4560.802 25625.45 > Itemp__2 -10666.18 3136.84 -3.40 0.011 -18083.63 -3248.734 > Itemp__3 1945.114 569.9302 3.41 0.011 597.4436 3292.785 > _cons .0053322 .0008244 6.47 0.000 .0033828 .0072815 > Deviance: -113.24. Best powers of temp among 164 models fit: -2 -2 -2. > > and I plug in these coefficients with my 'x' having a value of 25, my linear regression equation for predicting y is: > > y=.0053322+(15093.12*25^-2)+(-10666.18*25^-2*log(25))+1945.114*25^-2*(log(25))^2 > > However, this equation does not yield the same value as _predict_ (or _fracpred_), and this is because fracpoly secretly adjusts its constant. If I can calculate the answer to this equation and put it into a variable, I can then find the difference between this variable and the value that _fracpred_ gives. > > Thank you for your help. Hopefully this isn't too confusing. > > Chris > > > > > > * > * 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/

**Follow-Ups**:**Re: st: Re: using coefficients from model***From:*"Martin Weiss" <martin.weiss1@gmx.de>

**References**:**st: using coefficients from model***From:*Chris Witte <eljefespeaks@yahoo.com>

**st: Re: using coefficients from model***From:*"Martin Weiss" <martin.weiss1@gmx.de>

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