Running examples in ‘uwIntroStats-Ex.R’ failed
The error most likely occurred in:

> base::assign(".ptime", proc.time(), pos = "CheckExEnv")
> ### Name: regress
> ### Title: General Regression for an Arbitrary Functional
> ### Aliases: regress fitted.uRegress print.augCoefficients print.uRegress
> ###   uLRtest uWaldtest termTraverse explode indentNames getLevels testList
> ###   pasteTwo processTerm addArgs pasteOn pasteOnSpline pastePair
> ###   movingSum myNext reFormatReg createCols checkNesting splitOnParen
> ###   reFormat equal
> ### Keywords: ~kwd1 ~kwd2
> 
> ### ** Examples
> 
> # Loading required libraries
> library(survival)
> library(sandwich)
> 
> # Reading in a dataset
> mri <- read.table("http://www.emersonstatistics.com/datasets/mri.txt",header=TRUE)
> 
> # Creating a Surv object to reflect time to death
> mri$ttodth <- Surv(mri$obstime,mri$death)
> 
> # Attaching the mri dataset
> attach(mri)
> 
> # Linear regression of atrophy on age
> regress("mean", atrophy~age, data=mri)

Call:
regress(fnctl = "mean", formula = atrophy ~ age, data = mri)

Residuals:
    Min      1Q  Median      3Q     Max 
-36.870  -8.589  -0.870   7.666  51.203 

Coefficients:
                 Estimate  Naive SE  Robust SE    95%L      95%H     
[1] Intercept     -16.06     6.256     6.701       -29.22    -2.907  
[2] age            0.6980   0.08368   0.09002       0.5213    0.8747 
                    F stat    df Pr(>F)   
[1] Intercept            5.75 1    0.0168 
[2] age                 60.12 1  < 0.00005

Residual standard error: 12.36 on 733 degrees of freedom
Multiple R-squared:  0.08669,	Adjusted R-squared:  0.08545 
F-statistic: 60.12 on 1 and 733 DF,  p-value: 2.988e-14

> 
> ## Linear regression of atrophy on male and race and their interaction, 
> ## with a multiple-partial F-test on the race-age interaction
> regress("mean", atrophy~ male + U(ra=~race*age), data=mri)
Error in parse(text = x, keep.source = FALSE) : 
  <text>:1:8: unexpected symbol
1: atrophy`~`
           ^
Calls: regress ... formula -> formula.character -> formula -> eval -> parse
Execution halted