I haven't used it, but Incanter is a Clojure statistics and data analysis thing... http://incanter.org/

Not recommended. Matrix multiplication is really slow, even with Incanter. I doubt you'll get very far with data analysis without multiplying a few matrices so avoid.

Slow compared to what? Numpy (or equivalent) or optimized fortran?

I'm in the process right now. I didn't want to use Incanter since I don't like the kitchen sink reinvent R style, but there aren't any Clojure-esque matrix libraries around.

You, flatly, gain the language advantages of Clojure but have absolutely none of the Numpy/Matlab/R-like environments.

That is because Lisp has fractions as a native datatype. You would get the same result in Common Lisp.