The sample files are write protected and if you're new to Mac this can be an issue.
Here's how to undo that. (Thank you Bob Hickey!)
In a terminal window, change the directory to:
cd /Library/Application\ Support/JMP/12/Samples/Data
type ls -l to get a list of the files.
the characters before the file name reflect which user, group, other, all read write execute each file.
if you run
sudo chmod 777 *.jmp
and then enter your password the files can be read, write execute (rwx) by user, group other all
I think you have to do it for each directory in data for all the files, but most of them are in data.
If you are mac savvy and know this is a really bad idea or if you know how to do it to every *.jmp file in the application library all at once, please let me know.
Cheers,
B