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From |
Tinna <statalist@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

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

Date |
Tue, 18 Oct 2005 14:02:23 -0400 |

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/ > * * 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: RE: Graphing ploynomial relationships after a regression***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

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