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I want to plot a simple regression line in R. I've entered the data, but the regression line doesn't seem to be right. Can someone help?
x <- c(10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120)
y <- c(10, 18, 25, 29, 30, 28, 25, 22, 18, 15, 11, 8)
df <- data.frame(x,y)
plot(y,x)
abline(lm(y ~ x))
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A regression line will be added on the plot using the function abline(), which takes the output of lm() as an argument. You can also add a smoothing line using the function loess().
Adding a regression line on a ggplot You can use geom_smooth() with method = "lm" . This will automatically add a regression line for y ~ x to the plot.
The R function abline() can be used to add vertical, horizontal or regression lines to a graph. A simplified format of the abline() function is : abline(a=NULL, b=NULL, h=NULL, v=NULL, ...)
Oh, @GBR24 has nice formatted data. Then I'm going to elaborate a little bit based on my comment.
fit <- lm(y ~ poly(x, 3)) ## polynomial of degree 3
plot(x, y) ## scatter plot (colour: black)
x0 <- seq(min(x), max(x), length = 20) ## prediction grid
y0 <- predict.lm(fit, newdata = list(x = x0)) ## predicted values
lines(x0, y0, col = 2) ## add regression curve (colour: red)
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