SEQUENCE COMPARISON SIGNIFICANCE AND POISSON APPROXIMATION

The Chen-Stein method of Poisson approximation has been used to establ ish theorems about comparison of two DNA or protein sequences. The mos t useful result for sequence alignment applies to alignment scoring wi th no gaps. However, there has not been a valid method to assign stati stical significance to alignment scores with gaps. In this paper we ex tend Poisson approximation techniques using the Aldous clumping heuris tic to a practical method of estimating statistical significance.