abline not plotting in R

Question

CODE:

plot(medalswimmers$Height, medalswimmers$Weight , cex=1.3, pch=16, xlab="Height of medal winning swimmers (in years)", ylab="Respective weight of medal winning swimmers (in cm)")
lm(medalswimmers$Height ~ medalswimmers$Weight)

OUTPUT:

Call:
lm(formula = medalswimmers$Height ~ medalswimmers$Weight)

Coefficients:

(Intercept)  medalswimmers$Weight  
    129.2058                0.7146

CODE:

  abline(a = 129.2058, b= 0.7146, col="Blue") #-THIS DOES NOT PLOT???

An image of the plot without the regression line

Hi Draxler, your question is getting down voted because it is not reproducible so it is hard for us to help you. Also I believe in this case if you had taken the time to make a reproducible example you would likely have figured out what was going wrong. See here for some help: https://stackoverflow.com/q/5963269/3277050 — see24, Mar 13 '19 at 15:22

score 1 · Accepted Answer · answered Mar 13 '19 at 15:16

The line you are trying to plot is outside the plotting window. You can see this by calculating the y-value for the values of x at the limits of your plot:

# What value on the y-axis does the line have when x = 160?
> 129.2058 + 0.7146 * 160
[1] 243.5418

# What value on the y-axis does the line have when x = 200?
> 129.2058 + 0.7146 * 200
[1] 272.1258

The reason for this is you're plotting Height and Weight on the opposite axes to what you've entered in your linear model.

Try instead:

 l1 <- lm(Height ~ Weight, data=medalswimmers)

 plot(medalswimmers$Weight, medalswimmers$Height, cex=1.3, pch=16, 
      ylab="Height of medal winning swimmers (in years)", 
      xlab="Respective weight of medal winning swimmers (in cm)")

 abline(a=coef(l1)["(Intercept)"], b=coef(l1)["Weight"], color="blue")

abline not plotting in R

1 Answers1