J.doe J.doe - 2 months ago 17
R Question

plot regression line in R

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))


enter image description here

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Answer

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)

enter image description here

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