I recently came across a blog post (https://cssanalytics.wordpress.com/2014/02/12/probabilistic-momentum-spreadsheet/) that discusses calculating a t-stat as part of their model. However, the formula they use I can't seem to reconcile with the way I think a two sample t-test is calculated. Since I'm not not sure how to do the formatting for math symbols I'll type it in as the authors of the blog post have it in their excel sheet. (the link to the excel sheet is found in the post linked above)
I wouldn't expect the author to be wrong. How does this work as a t-stat?