Before revision:  The leave-one-out LSM (LOOLSM) method is illustrated with examples, including  multi-asset options whose LSM price is biased high. The asymptotic behavior of look-ahead bias is also discussed with the LOOLSM approach .
After revision:  The leave-one-out LSM (LOOLSM) method is illustrated with examples, including multi-asset cases that the LSM algorithm significantly overvalues. We also obtain the convergence rates of look-ahead bias is also discussed with the LOOLSM approach .