what is the hidden stat for basement ending in rye route.
I believe there's a hidden "Rye Loyalty" stat, which indicates how much she's willing to defy her mother for you. This can be raised via dialogue options and some choices (such as going dutch on the bondage gear), but really, try to avoid leaving her alone with her mother; that's what causes the checks.
Unless you meant the hidden anal stat during the sex scene, which I don't think is passable.