Seems like you are offering the same data manipulation people currently do either with desktop software or custom coded server apps. Your value here is turning it into a web service and making it easier to use. There is a very strong case for doing just that.

What I would recommend is to connect the dots and clearly position your service as cloud alternative to desktop / server data manipulation packages. Get very explicit about it and target similar customers. Do not limit yourself to just data on the web and allow file uploads. Make a feature-light free version and charge for a premium one, determined by data volume or number of manipulations or something like that.

I think there is a lot of room for cloud-based statistical service to undercut traditional players in this market.