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

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

Subject |
RE: st: RE: Graphing ploynomial relationships after a regression |

Date |
Tue, 18 Oct 2005 19:13:16 +0100 |

That's good. Do join in. Nick n.j.cox@durham.ac.uk > -----Original Message----- > From: owner-statalist@hsphsun2.harvard.edu > [mailto:owner-statalist@hsphsun2.harvard.edu]On Behalf Of Tinna > Sent: 18 October 2005 19:02 > To: statalist@hsphsun2.harvard.edu > Subject: Re: st: RE: Graphing ploynomial relationships after a > regression > > > Hello Maarten and Nick, > > I do not mean to stop your discussion, which I am learning a bunch > from, but I wanted to thank you and tell you that I have my desired > graph now. > > Tinna > > On 10/18/05, Nick Cox <n.j.cox@durham.ac.uk> wrote: > > As a model gets more complex, it is less likely that it can > > be presented by a graph. y = polynomial(x) is one exception, but > > in practice even cubics over a whole range are unlikely to be > > useful, in my experience. > > > > But, more to the point, a model gets more complex, you have _more_ > > to type as you spell out each term as _b[varname] * > varname. -predict- > > does this all for you. And this is error-prone. > > > > Other than the occasional pedagogic advantage of underlining > > what is being done, i.e. plugging estimates into a model > > formula, I can't understand your preference here. > > > > Nick > > n.j.cox@durham.ac.uk > > > > Maarten Buis > > > > > True, though I find it easier to continue to use my approach > > > when my model gets more complex. > > > > > > n j cox wrote: > > > > > > > Even with Maarten's example, things can be made > > > > simpler. Starting as before, > > > > > > > > sysuse auto, clear > > > > gen weight2 = weight^2 > > > > reg price weight weight2 > > > > > > > > if you > > > > > > > > predict quad > > > > twoway mspline quad weight || scatter price weight > > > > > > > > you get the data shown as well. > > > > > > > > Alternatively, if you install the -modeldiag- package > > > > from either SSC or the Stata website, then > > > > > > > > predict quad > > > > regplot > > > > > > > > will give you the same graph. This is because -regplot- > > > > defaults to a plot of the observed and predicted response > > > > against the first predictor named. > > > > > > > > Maarten Buis > > > > > > > > sysuse auto, clear > > > > gen weight2 = weight^2 > > > > reg price weight weight2 > > > > sum weight > > > > twoway function y = _b[_cons]+_b[weight]*x+_b[weight2]*x^2, > > > range(1760 > > > > 4840) > > > > > > > > > > > > Tinna > > > > > > > > I am using an independent variable in its regular and > > > squared forms in > > > > an OLS and 2SLS regressions. Can I graph this polynomial > > > relationship > > > > as indicated by the regression in an easy way? * * 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/

**Follow-Ups**:**Re: st: RE: Graphing ploynomial relationships after a regression***From:*Tinna <statalist@gmail.com>

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