From: Lance Westerhoff <lance_at_quantumbioinc.com>

Date: Wed 25 Jan 2006 - 03:50:43 EST

Date: Wed 25 Jan 2006 - 03:50:43 EST

To begin, I have a set of data points in which the y is the experimental number and x is the predicted value. The Excel- generated graph (complete with R^2 and trend line) is provided at this link if you want to take a look:

http://www.quantumbioinc.com/downloads/public/excel.png

As you can see, the R-squared that is reported by Excel is -0.1005. Now when I bring the same data into R, I get an R-square of +0.9331 (see below). Being that I am new to R and semi-new to stats, is there a difference between "multiple R-squared" and R-squared that perhaps I am simply interpreting this wrong, or is this a known inconsistency between the two applications? If so, which is correct? Any insight would be greatly appreciated!

> # note: a is experimental and c is predicted

> summary(lm(a~c-1))

Min 1Q Median 3Q Max -2987.6 -1126.6 -181.7 855.3 5602.8

Estimate Std. Error t value Pr(>|t|)

c 0.99999 0.01402 71.33 <2e-16 ***

--- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 Residual standard error: 1423 on 365 degrees of freedom Multiple R-Squared: 0.9331, Adjusted R-squared: 0.9329 F-statistic: 5088 on 1 and 365 DF, p-value: < 2.2e-16Received on Wed Jan 25 04:00:00 2006

> version

_ platform powerpc-apple-darwin7.9.0 arch powerpc os darwin7.9.0 system powerpc, darwin7.9.0 status major 2 minor 2.1 year 2005 month 12 day 20 svn rev 36812 language R ====================== Thank you very much for your time! -Lance ____________________ Lance M. Westerhoff, Ph.D. General Manager QuantumBio Inc. WWW: http://www.quantumbioinc.com Email: lance@quantumbioinc.com "Safety is not the most important thing. I know this sounds like heresy, but it is a truth that must be embraced in order to do exploration. The most important thing is to actually go." ~ James Cameron ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html

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