Unable to unzip/install latest version of PSPP

[Barth Riley]

Dear list

I realize this is a very basic question. I am trying to install the 
latest version of PSPP from the GNU site. After downloading the file 
(from various sources,--GNU, GNU mirror and FTP) I double clicked on the 
.tar.gz file and I receive an error message that the command line is 
invalid...? I also receive this message when I try to open the file from 
the 7 Zip application. Has anyone on the list encountered this problem? 
Any suggestions for a workaround?

thanks in advance

--
Barth