lm() 和 geom_smooth() 的参数是否相同？

Question

I am wondering if the function lm() from the stats package is the same as the one used in geom_smoot(method = lm) in ggplot2. If so, are the parameters calculated by them the same everytime for the same data.

So would...

lm(response ~ variable, data = dat)

calculate the same parameters as...

ggplot(dat, aes(variable, response)) + 
  geom_smooth(method = lm)

Answer 1

Yes, geom_smooth uses stats::lm . The ?geom_smooth documentation mentions stats::lm specifically, and in the See Also section has a link to the lm documentation.

Answer 2

The linear model (coded in lm ) is fully deterministic. It returns the same results as long as you call it on the same input. geom_smooth uses stats::lm behind the scene, so the results should be the same. Note that it is not possible to extract model parameters from a ggplot plot ( link ).