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Cheers, Bert Bert Gunter Genentech Nonclinical Biostatistics (650) 467-7374 "Data is not information. Information is not knowledge. And knowledge is certainly not wisdom." Clifford Stoll On Tue, Aug 19, 2014 at 11:09 AM, sam cruickshank <sam_l_cruicksh...@hotmail.com> wrote: > > > > > > Good afternoon, > I am completed a linear regression model which I personally am happy with the > output and residual charts (although they are a bit bunched). I have been > using visreg() to visualise my data, and although I have logged the dependent > variable (as it is cost data), on one of the graphical outputs I am getting > negative fitted values for one of the Continents. Attached is the data used, > below is the code for the model and graph. If anyone has any ideas I would > hugely appreciate it, I tried a glm with log link too and this didn't help. > LM22 <- lm(logTotal ~ logArea + Continent + factor(Method1) + Popdens, > data=dummy) > Output Residuals: Min 1Q Median 3Q Max -1.22742 > -0.31675 -0.00909 0.28885 1.20224 > Coefficients: Estimate Std. Error t value Pr(>|t|) > (Intercept) -1.40972 0.77661 -1.815 0.081506 . logArea > 0.03811 0.04041 0.943 0.354619 ContinentAsia > 3.51165 0.80009 4.389 0.000182 ***ContinentAustralasia 3.48549 > 0.97433 3.577 0.001454 ** ContinentEurope 2.44829 0.82369 > 2.972 0.006452 ** ContinentGlobal 2.37910 1.00668 2.363 0.026197 > * ContinentNorth America 2.27953 0.62960 3.621 0.001303 ** > ContinentSouth America 3.60997 0.77627 4.650 9.22e-05 > ***factor(Method1)2 1.11259 0.38386 2.898 0.007696 ** > factor(Method1)3 0.82519 0.47470 1.738 0.094459 . > factor(Method1)4 -0.06737 0.67341 -0.100 0.921104 Popdens > -0.14261 0.31675 -0.450 0.656435 ---Signif. codes: 0 ‘***’ > 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 > Residual standard error: 0.6151 on 25 degrees of freedom (12 observations > deleted due to missingness)Multiple R-squared: 0.6998, Adjusted > R-squared: 0.5677 F-statistic: 5.297 on 11 and 25 DF, p-value: 0.0002714 > visreg(LM22) gives me a graph with "Africa" being within the realm of > negative "Total" which is impossible. If you tell me how can provide the > data and graphs, but the email was kicked back with them in. > [[alternative HTML version deleted]] > > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
