MOTIVATION: The efficient and accurate computation of P-values is an essential requirement for motif-finding and alignment tools. We show that the approximation algorithms used in two popular motif-finding programs, MEME and Consensus, can fail to accurately compute the P-value. RESULTS: We present two new algorithms: one for the evaluation of the P-values of a range of motif scores, and a faster one for the evaluation of the P-value of a single motif score. Both exhibit more reliability than existing algorithms, and the latter algorithm is comparable in speed to the fastest existing method. AVAILABILITY: The algorithms described in this paper are available from http://www.cs.cornell.edu/~keich
MOTIVATION: The efficient and accurate computation of P-values is an essential requirement for motif-finding and alignment tools. We show that the approximation algorithms used in two popular motif-finding programs, MEME and Consensus, can fail to accurately compute the P-value. RESULTS: We present two new algorithms: one for the evaluation of the P-values of a range of motif scores, and a faster one for the evaluation of the P-value of a single motif score. Both exhibit more reliability than existing algorithms, and the latter algorithm is comparable in speed to the fastest existing method. AVAILABILITY: The algorithms described in this paper are available from http://www.cs.cornell.edu/~keich