normcheck {s20x} | R Documentation |
Plots two plots side by side. Firstly it draws a Normal QQ-plot of the residuals, along with a line which has an intercept at the mean of the residuals and a slope equal to the standard deviation of the residuals. In the top left hand corner, the P-value from the Shapiro-Wilk test for normality is given. Secondly, it draws a histogram of the residuals. A normal distribution is fitted and superimposed over the histogram.
normcheck(x, ...) ## Default S3 method: normcheck (x, xlab = NULL, col = NULL, ...) ## S3 method for class 'lm': normcheck (x, xlab = NULL, col = NULL, ...)
x |
the residuals from fitting a linear model. Alternatively, a fitted lm object. |
xlab |
a title for the x axis: see title . |
col |
a color for the bars of the histogram. |
... |
Optional arguments |
"shapiro.test"
# An exponential growth curve e<-rnorm(100,0,0.1) x<-rnorm(100) y<-exp(5+3*x+e) fit<-lm(y~x) normcheck(fit) # An exponential growth curve with the correct transformation fit<-lm(log(y)~x) normcheck(fit) # Same example as above except we use normcheck.default normcheck(residuals(fit)) # Peruvian Indians data data(peru.df) normcheck(lm(BP~weight, data=peru.df))