We study and compare two classes of statistical criteria to assess the significance of exceptional words. Indeed, the zscore-like criteria, or the normal approximation that is a strict equivalent, suffer from several drawbacks in terms of sensitivity and specificity. Thanks to the combinatorial structure of words, a computation of the exact pvalue has been made possible by recent mathematical results. We study here the drawbacks of the zscore, the choice of the threshold and the tightness to the pvalue. A major conclusion is that the normal approximation is always very poor and overestimates statistical significance.
In REF , the drawbacks of the Gaussian approximation are analyzed.
Comparison of Statistical Significance Criteria
Journal of bioinformatics and computational biology
Journal of bioinformatics and computational biology
Mathematics Medicine Computer Science