ggplot2: how to get values for the regression line equation, r^2 and p value?

Question

I cant work out how to get the regression line equation, r^2 and p value of the linear regression I have plotted using the function geom_smooth.

This is my code:

   g <- ggplot(data=data.male, aes(x=mid_year, y=mean_tc, colour=data.male$survey_type))  
   g <- g + geom_point(shape = 20, size =2) 
   g <- g + geom_smooth(method=lm, na.rm = FALSE, se = TRUE, aes(group=1), colour = "black")
   g <- g + theme_gray(base_size=24)
   g <- g+ xlab("Year")
   g <- g + ylab("Mean serum total cholesterol (mmol/L)")
   g <- g + theme(legend.position="bottom")
   g <- g + scale_y_continuous(limits=c(3.5,6.5), breaks=c(3.5,4,4.5,5,5.5,6,6.5))
   g <- g + scale_x_continuous(limits=c(1980,2015), breaks=c(1980,1990,2000,2010))
   g <- g + scale_colour_manual(name = "Survey Type", values= c("Red", "Blue", "Green")) 
   g  

[1]:

Answer 1

Don't use a plotting function for modelling. Fit the model using the lm function.

Then use the summary method to get everything you need to know about the fit.

You should get the same results as the plotting function, which I suspect uses lm internally.