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

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

Subject |
st: RE: logit and LOESS graphs |

Date |
Fri, 7 Mar 2008 19:54:41 -0000 |

In addition to Maarten's comments: 1. What was first called lowess was later called loess (and is also implemented in other languages as locfit). Stata has stuck to the name -lowess- for some time. No matter, in Stata . search loess would have pointed Chris to helpful documentation. The name -loess- is at least for some users most unfortunate as it refers to a particular kind of deposit much studied by sedimentologists and geomorphologists (and not a smooth surface as Bill Cleveland claims somewhere). No matter! 2. A logit curve, depending quite what is meant by that, can be obtained pure and simple by twoway function logit = logit(x) twoway function inverse_logit = invlogit(x), ra(-5 5) 3. If you install -regplot- (-findit regplot- for locations), then another way to get part of Maarten's example is logit foreign mpg regplot Nick n.j.cox@durham.ac.uk Maarten buis --- Chris wrote: > 1. Does anyone know how to perform LOESS in Stata? I know how to do > this in R but I'd prefer to avoid that, because R is memory > inefficient. > > 2. Is there a way to display a logit curve? Given the combination of question I am assuming you are looking for something like the example below. However, there ares some weird jumps in the lowess curve that I cannot explain. -- Maarten *----------- begin example ------------------ sysuse auto, clear logit foreign mpg sort mpg predict logit, xb predict pr, pr twoway lowess foreign mpg || /// line pr mpg, name(pr) twoway lowess foreign mpg, logit || /// line logit mpg, name(logit) *----------------- end example ----------------- * * 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**:**st: logit and LOESS graphs***From:*Maarten buis <maartenbuis@yahoo.co.uk>

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