Confidence intervals should be used in reporting trials

EDITOR—The dispute between Barber and Thompson,1 who are advocating a t test, and Williams, Cohen, and Russell, who are advocating a Mann-Whitney U test,2 has its roots in the use of P values rather than confidence intervals. If Williams et al had reported their results as a confidence interval for the difference in mean cost, as recommended for the results of clinical trials published in the BMJ, the question would not have arisen. The sample …