Best Statistical Add-On To Excel?

Hello everyone,

I was hoping someone could tell me what the best statistical addons are to excel that are under $400?

I was looking at StatTools. Has anyone used it, and is it recommended? Is there a better one out there?




How bout free? Check out R. Or even better what if you just forgot about excel all together? R does have a package that works with excel though, however I've never used it.
If your application involves linear regression and/or multivariate data analysis, you should check out RegressIt, a *free* add-on for Excel for Windows, at It is very powerful but also extremely easy to use, and it offers better quality graphics than most commercial stat software. It also has a number of novel features that support best practices of data analysis. It doesn't require permanent installation--just launch it as needed.