pull out p-values and r-squared from a linear regression
Solution 1
r-squared: You can return the r-squared value directly from the summary object summary(fit)$r.squared
. See names(summary(fit))
for a list of all the items you can extract directly.
Model p-value: If you want to obtain the p-value of the overall regression model, this blog post outlines a function to return the p-value:
lmp <- function (modelobject) {
if (class(modelobject) != "lm") stop("Not an object of class 'lm' ")
f <- summary(modelobject)$fstatistic
p <- pf(f[1],f[2],f[3],lower.tail=F)
attributes(p) <- NULL
return(p)
}
> lmp(fit)
[1] 1.622665e-05
In the case of a simple regression with one predictor, the model p-value and the p-value for the coefficient will be the same.
Coefficient p-values: If you have more than one predictor, then the above will return the model p-value, and the p-value for coefficients can be extracted using:
summary(fit)$coefficients[,4]
Alternatively, you can grab the p-value of coefficients from the anova(fit)
object in a similar fashion to the summary object above.
Solution 2
Notice that summary(fit)
generates an object with all the information you need. The beta, se, t and p vectors are stored in it. Get the p-values by selecting the 4th column of the coefficients matrix (stored in the summary object):
summary(fit)$coefficients[,4]
summary(fit)$r.squared
Try str(summary(fit))
to see all the info that this object contains.
Edit: I had misread Chase's answer which basically tells you how to get to what I give here.
Solution 3
You can see the structure of the object returned by summary()
by calling str(summary(fit))
. Each piece can be accessed using $
. The p-value for the F statistic is more easily had from the object returned by anova
.
Concisely, you can do this:
rSquared <- summary(fit)$r.squared
pVal <- anova(fit)$'Pr(>F)'[1]
Solution 4
I came across this question while exploring suggested solutions for a similar problem; I presume that for future reference it may be worthwhile to update the available list of answer with a solution utilising the broom
package.
Sample code
x = cumsum(c(0, runif(100, -1, +1)))
y = cumsum(c(0, runif(100, -1, +1)))
fit = lm(y ~ x)
require(broom)
glance(fit)
Results
>> glance(fit)
r.squared adj.r.squared sigma statistic p.value df logLik AIC BIC deviance df.residual
1 0.5442762 0.5396729 1.502943 118.2368 1.3719e-18 2 -183.4527 372.9055 380.7508 223.6251 99
Side notes
I find the glance
function is useful as it neatly summarises the key values. The results are stored as a data.frame
which makes further manipulation easy:
>> class(glance(fit))
[1] "data.frame"
Solution 5
While both of the answers above are good, the procedure for extracting parts of objects is more general.
In many cases, functions return lists, and the individual components can be accessed using str()
which will print the components along with their names. You can then access them using the $ operator, i.e. myobject$componentname
.
In the case of lm objects, there are a number of predefined methods one can use such as coef()
, resid()
, summary()
etc, but you won't always be so lucky.
Related videos on Youtube
grautur
Updated on December 30, 2020Comments
-
grautur over 3 years
How do you pull out the p-value (for the significance of the coefficient of the single explanatory variable being non-zero) and R-squared value from a simple linear regression model? For example...
x = cumsum(c(0, runif(100, -1, +1))) y = cumsum(c(0, runif(100, -1, +1))) fit = lm(y ~ x) summary(fit)
I know that
summary(fit)
displays the p-value and R-squared value, but I want to be able to stick these into other variables. -
hadley over 12 yearsIt's a bit better to use
inherits
rather thanclass
directly. And maybe you wantunname(pf(f[1],f[2],f[3],lower.tail=F))
? -
Bakaburg over 9 yearsthis works only for univariate regressions where the p val of the regression is the same of the predictor
-
António Ribeiro about 8 yearsCare to provide an explanation, even if briefly, on why this code works?
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Ben Bolker about 8 yearshow does this improve on the existing answers (and in particular the accepted answer)?
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j_v_wow_d over 7 yearsI tried this method, but it will fail if the linear model contains any NA terms
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Andrew Brēza about 4 yearsThis is a great answer!
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Comfort Eagle over 3 yearsIf you prefer a one-liner:
summary(fit)$fstatistic %>% {unname(pf(.[1],.[2],.[3],lower.tail=F))}
-
Comfort Eagle over 3 yearsOr as pipe-less one-liner:
with(summary(fit), pf(fstatistic[1],fstatistic[2],fstatistic[3],lower.tail=F))