http://www.biomedcentral.com/1471-2288/4/13/comments The latest comments on the article 'Incongruence between test statistics and Pvalues in medical papers' 2006-05-15T00:00:00Z This is an RSS newsfeed from BioMed Central It is intended to be used with an RSS reader. For more information about RSS newsfeeds from BioMed Central, visit http://www.biomedcentral.com/info/about/rss/ http://www.biomedcentral.com/1471-2288/4/13/comments#235529 <p>Deficiencies of software are, to our knowledge, often. We recently compared 3 programs - Statistix, Analyse-it, MedCalc. The respective zero hypothesis were tested in 5 artificially created data sets by the parametric unpaired t-test, non-parametric Mann-Whitney test, two-tailed F-test. The p values in the same tests were mutually compared.</p><p>All three programs calculated identical exact p values for the t-test. In the remaining two tests in case of 26 out of 44 calculations (59.1 %; 95 % confidence interval 43 to 73 %) different p values were calculated. The greatest difference was 18.35 %. In two cases the values oscillated about 0.05 and this fact caused essentially different interpretation of results.</p><p>Our discoveries should undermine the ungrounded belief of the users of statistical tests physicians in ununderminable accuracy of mathematical procedures.</p><p>Ref. 1. Gasko, R. Statistical hypothesis testing - how exact are exact p-values? Bratisl Lek Listy 2003; 104: 36-39. Free full text on www.bmj.sk </p> Rudolf Gasko 2006-05-15T00:00:00Z