[R] Extract statistics from lm()
Tobias Verbeke
tobias.verbeke at openanalytics.be
Sat Feb 28 20:31:05 CET 2009
Hi,
> Hi, perhaps this question was answered previously however I could not find
> them. My problem is how how to extract a particular statistic from the
> result given by lm(). For e.g.
>
> ctl <- c(4.17,5.58,5.18,6.11,4.50,4.61,5.17,4.53,5.33,5.14)
> trt <- c(4.81,4.17,4.41,3.59,5.87,3.83,6.03,4.89,4.32,4.69)
> group <- gl(2,10,20, labels=c("Ctl","Trt"))
> weight <- c(ctl, trt)
>> summary(lm.D9 <- lm(weight ~ group))
>
> Call:
> lm(formula = weight ~ group)
>
> Residuals:
> Min 1Q Median 3Q Max
> -1.0710 -0.4938 0.0685 0.2462 1.3690
>
> Coefficients:
> Estimate Std. Error t value Pr(>|t|)
> (Intercept) 5.0320 0.2202 22.850 9.55e-15 ***
> groupTrt -0.3710 0.3114 -1.191 0.249
> ---
> Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
>
> Residual standard error: 0.6964 on 18 degrees of freedom
> Multiple R-squared: 0.07308, Adjusted R-squared: 0.02158
> F-statistic: 1.419 on 1 and 18 DF, p-value: 0.249
>
>
> Here I want to extract the values of "t-stat", "Pr(>|t|)" individually. Can
> anyone please guide me how to get them?
summaryD9 <- summary(lm.D9 <- lm(weight ~ group))
(coefD9 <- coef(summaryD9))
coefD9[, "t value"]
coefD9[, "Pr(>|t|)"]
In order to get an overview of the structure of an object
you can use the str function as in:
str(summaryD9)
HTH,
Tobias
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