Newbie RStudio Syntax Question

[taylor1956]

I am using "Statistics Using R For Dummies" to self--teach. On one exercise:

1. I installed "mass" package
   .2. I installed and opened "edit" for the"mass" subfile ("anorexia'). The "Data Editor red and white spreadsheet for "anorexia" data opened up. So far, so good.

Here's where the problem begins:
The text tells me to type: anorexia$Postwt-anorexia$Prewt, but nothing happens in console except a repeat in blue of what I typed. Ditto for the t-test syntax in text associated with "anorexia" file.
Can anyone tell me what I'm doing wrong?

[andresrcs]

I'm making some assumptions here since you haven't shared a reproducible example, but maybe you are trying to do this t.test(anorexia$Postwt, anorexia$Prewt)