Before I do this on my own, I wonder if there are any statistics class out there that for example will take an array of figures and return Z-scores, standard deviation and so forth. I mean, I can write something to do the simple stuff, but I suspect someone may have done something that includes a lot more advanced things that would be very useful and save time.

some maths routines with big numbers here : http://delaneyrm.com/index.html

but no stats apart from the gamma function.

Been looking for this myself - came across this: https://forum.xojo.com/18558-is-there-a-way-to-get-the-average-in-an-array-of-integers-via-t/5

these are easy to port to xojo, and are free to use :

http://www.kurims.kyoto-u.ac.jp/~ooura/index.html

Came across this: https://www.gnu.org/software/gsl/doc/html/index.html

Seems quite comprehensive and written in C, so should be able to be ported to XOJO

Did you have a look at MathScriptor? I could only find a copy via the Wayback machine but it might be a useful starting point. Download the starter pack.

http://web.archive.org/web/20160413133438/http://chembio.chem.uconn.edu/Mathscriptor.html

Now if Robert Birge and Bob Delaney could get together they are probably the most qualified to start a statistics project