I know people bag on VBA, but I'm a big advocate of effectively utilizing Excels tools along side using VBA to customize where necessary. This solves the problem in your first comment (users can define their own statistical limits and methods), while keeping the simplicity of excel and its tools for other users.

The problem is that not everyone is a programmer. A "programming" tool might be great for you, but when you show it to co-workers for them to work with, they'll inevitably ask "Can I get this in Excel?". Excel+VBA allows for customization when the "complexity/ease-of-use" balance is out of sync with your needs, but to everyone else it's still just Excel.

With this, those that can program have the option to solve the problem their way, while allowing those that don't program the means to solve the problem the way their used to.