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From |
"James Xiao" <JXiao@americanlegacy.org> |

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

Subject |
st: Venn diagram |

Date |
Tue, 4 May 2004 17:59:13 -0400 |

Dear listers, I'm trying to use venndiag ado-files to draw a two variable venn diagram. The following is the result I got, but no graph pop out. . venndiag currsmk obesity ______________________________________________________________________ Venn diagram of variables: currsmk obesity File: H:\My Documents\NHIS\2002 NHIS\dataset\samadult.dta ( 4 May 2004 ) Outcome Variable and label A: 1 currsmk currsmk B: 1 obesity obesity 31044 Records in file 330 Records excluded by missing values _____ 30714 Records in Diagram: Counts for combined variables: ---------------------------------------------------------------------- A | 5298 17 % (currsmk == 1)& (obesity != 1) B | 6843 22 % (currsmk != 1)& (obesity == 1) AB | 1621 5 % (currsmk == 1)& (obesity == 1) -- | 16952 55 % (currsmk != 1)& (obesity != 1) ---------------------------------------------------------------------- ______________________________________________________________________ file C:\DOCUME~1\jxiao\LOCALS~1\Temp\ST_03000016.tmp saved obs was 0, now 1001 file C:\DOCUME~1\jxiao\LOCALS~1\Temp\ST_03000017.tmp saved obs was 0, now 1001 Did anybody use this ado-file before? I just got it from stata update. Any suggestions are highly appreicated!!! James Xiao -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of khigbee@stata.com Sent: Tuesday, May 04, 2004 5:49 PM To: statalist@hsphsun2.harvard.edu Subject: Re: st: About coliearity Maoyong Fan <fan@berkeley.edu> asks: > I am running some ordinary least regression now. There are more than > 50 explainary variables in my model. Most of them are dummy > variables. The Stata will automatically drop the variables randomly > if the variable cause colinearity. However, I want to keep some > important variables in my regression and drop only those dummy > variables when the important variable and dummy variable cause > colinearity. How can I program to do this? I hope that someone else will think up a clever solution different from what I am about to suggest, and I hesitate to show the following undocumented feature ... but I think it will solve your problem. I only ask that you (and anyone else venturing along the path I am about to show) be careful when using the feature. First some background information. Stata when determining and correcting for collinearity (by default) tries to pick one of the collinear variables to drop based on which drop will provide the most stable numeric properties. As Maoyong Fan points out, for near ties in this criteria (not uncommon in this setting), the choice may differ from one run to another. Underneath the hood (or should I say bonnet) Stata is using the sweep operator on the X'X matrix. By default with -regress- (etc.), Stata will (behind the scenes) reorder the rows and columns of the matrix so that the most stable variables are retained when it comes to a decision of collinearity (i.e., when it encounters a near zero element on the diagonal during the sweep). There is an internal flag that turns off this behavior. It is used for -anova- and -manova-, because in those cases we want higher order interaction indicators (often called dummies) to be dropped before main effects and lower interactions. We set up the X'X with the constant first, the main effects next, then the interactions with highest order interactions last. We turn off the flag, and then we sweep. When done we turn back on the flag for whatever command that might follow. It sounds like this is similar to what you want to achieve. If just before you call your estimation command you enter . set debug on . set tol r 0 . set debug off then the reorder flag will be turned off. Then you run your estimation command placing the variables in importance order left to right. (The right most colinear vars will be dropped before those further to the left.) IMPORTANT ! -- turn the flag back on after you are done. . set debug on . set tol r 1 . set debug off so that Stata will be back to normal behavior. This is what I meant when I asked that anyone doing this be careful. Make sure you get Stata back to its default behavior. Ken Higbee khigbee@stata.com StataCorp 1-800-STATAPC * * 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/

**Follow-Ups**:**Re: st: Venn diagram***From:*Friedrich Huebler <huebler@rocketmail.com>

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