CODEWITHSUNDEEP
rplot
adam.888
adam.888

Reputation: 7846

R plot linear regression and standard deviation using abline

I can plot a linear regression line using abline: 

x= runif(10)
y=runif(10)
fit1 <- lm(x ~ y )
sd2 <- sd(abs(fit1$residuals))*2

plot(x,y)
abline(fit1)

But how can I plot the standard deviation lines using abline. I tried:

abline(fit1+sd2)
abline(fit1-sd2)

but I get an error. Thank you for your help.

Upvotes: 1

Views: 5760

Answers (2)

gsun
gsun

Reputation: 427

abline(fit) works because it takes in intercept and slope from fit to draw the line, it is identical to my second line of code. So abline with sd2 can work if we move the line upp sd2 units and down sd2 units. You can achieve it by my third and fourth lines.
plot(x,y) abline(fit1$coefficients[1],fit1$coefficients[2]) abline(fit1$coefficients[1]+sd2,fit1$coefficients[2]) abline(fit1$coefficients[1]-sd2,fit1$coefficients[2])

Hope this explanation of abline is helpful.

Upvotes: 3

Wietze314
Wietze314

Reputation: 6020

You can use ggplot to achieve this:

x= runif(10)
y=runif(10)
fit1 <- lm(x ~ y )
sd2 <- sd(fit1$residuals)

library(ggplot2)

ggplot(data.frame(x,y), aes(x=x,y=y)) + 
geom_point() + 
geom_smooth(method="lm")

Upvotes: 2

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