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

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

Subject |
st: RE: Regplot Problems! |

Date |
Wed, 19 Feb 2003 18:50:58 -0000 |

Al-Zakwani, Ibrahim > Just to add to a question that was posted earlier regarding > <regplot> > I am also experiencing problems.. > Below, please find the output.. > I would appreciate any insight as to what might be a problem... > I am using Stata version 8 - Windows 2000 > Thanking you in advance.. > > Ibrahim > > > . sysuse auto > (1978 Automobile Data) > > . regress foreign > > Source | SS df MS > Number of obs = > 74 > -------------+------------------------------ F( > 0, 73) = > 0.00 > Model | 0 0 . Prob > > F = > . > Residual | 15.4594595 73 .211773417 > R-squared = > 0.0000 > -------------+------------------------------ Adj > R-squared = > 0.0000 > Total | 15.4594595 73 .211773417 Root > MSE = > .46019 > > ------------------------------------------------------------ > ---------------- > -- > foreign | Coef. Std. Err. t P>|t| [95% Conf. > Interval] > -------------+---------------------------------------------- > ---------------- > -- > _cons | .2972973 .0534958 5.56 0.000 .1906803 > .4039143 > ------------------------------------------------------------ > ---------------- > -- > > . regplot > variable _cons not found > no variables defined > no variables defined > r(111); > This one's different. You fitted a regression with response and no predictor. That's perfectly meaningful and -regress- bounced back the mean of foreign at you. However, -regplot- expects to pick up a predictor from among the -regress- results, but it can only find _cons, and Stata tells -regplot- that no such variable exists, because _cons is just Stata jargon for the intercept. There is an interesting little question of program design here. I as programmer should trap this. I can think of two possibilities. 1. You want this ================ . regress foreign was entirely deliberate and you do want to see -regplot-, which would be a single horizontal line y = mean of foreign and anything you like on the horizontal axis. That wouldn't be tremendously interesting or useful but it would be valid, except that it would be quite arbitrary what I plot the data for foreign against. 2. You made a mistake ===================== You forgot to specify a predictor and haven't spotted that yet. -regplot- should say, "Excuse me, no predictor variable". I incline to 2. Nick n.j.cox@durham.ac.uk * * 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: Regplot Problems!***From:*"Al-Zakwani, Ibrahim" <IAl-Zakwani@healthcore.com>

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