I just heard recently about PSPP, which is a free, open source version of SPSS.
I have not tried it yet, but it does look promising. This is the description from its website:
It is a Free replacement for the proprietary program SPSS, and appears very similar to it with a few exceptions.
The most important of these exceptions are, that there are no “time bombs”; your copy of PSPP will not “expire” or deliberately stop working in the future. Neither are there any artificial limits on the number of cases or variables which you can use. There are no additional packages to purchase in order to get “advanced” functions; all functionality that PSPP currently supports is in the core package.
PSPP can perform descriptive statistics, T-tests, linear regression and non-parametric tests. Its backend is designed to perform its analyses as fast as possible, regardless of the size of the input data. You can use PSPP with its graphical interface or the more traditional syntax commands.
Sounds pretty good, huh?
The only downside I can see, though, is with the statement “no additional packages to purchase in order to get ‘advanced’ functions.” That appears to be because there aren’t any advanced functions. PSPP seems to correspond only to SPSS base. No Advanced Models, no Missing Values Analysis, no Complex Surveys. That means you can do one-way ANOVA and regression, but not GLM, logisitic regression, factor analysis.
So if you are only using SPSS for basic statistics, or for teaching an intro class, this may be just what you need. And perhaps if it takes off, as R has, we’ll see more advanced features soon.
If you’ve had any experience using PSPP, please tell me about it in a comment. I’d love to hear how well it works.