Chapter 17 FAQs

Why am I getting weird variable names?

Unfortunately this can happen on windows computers.You can fix it with the following code

names(smoking)[1] = "Age"

This code looks at the column names, picks the first one, and then reassigns it to Age.

How do I produce a residual plot with missing values in data?

library(ggplot2)
help(msleep)
plot(sleep$bodywt, sleep$brainwt)
L = lm(sleep$brainwt ~ sleep$bodywt)
summary(L)
abline(L)

# Correlation (with missing values)
length(sleep$bodywt) 
length(sleep$brainwt) 
cor(sleep$bodywt, sleep$brainwt, use = "complete.obs")  


# Residual plot (with missing values)
length(sleep$bodywt) 
length(L$residuals)
residuals1 = resid(lm(sleep$brainwt ~ sleep$bodywt, na.action=na.exclude)) 
length(residuals1)
plot(sleep$bodywt,residuals1)