Stayman in doubt (SID) is an extension to Stayman, showing a completely balanced hand with 4-3-3-3 distribution with a fit with the opener. The motivation is that, with exactly 4-3-3-3 hands in both the opener and the responder, there is no short suit to ruff, so that a notrump contract probably produces the same number of tricks as the major suit contract. Therefore, 3NT may be preferable than 4 of the major in this case, since it requires one trick less to make and is worth 10 points more when the same number of tricks are taken.