Before revision:  This study proposes a new approach for efficiently eliminating look-ahead bias by using the leave-one-out method , a well-known cross-validation technique for machine learning applications. The leave-one-out LSM (LOOLSM) method is illustrated with examples, including  multi-asset options whose LSM price is biased high.
After revision:  This study proposes a new approach for efficiently eliminating look-ahead bias . We validate the method with several option examples, including multi-asset options whose LSM price is biased high.