What is the chance that this study is clinically significant? A proposal for Q values.
BACKGROUND
Clinicians who use the medical literature to guide their practice need to make judgments about the clinical significance of medical interventions.


OBJECTIVE
How likely is an intervention to be clinically worthwhile?


OBJECTIVE
Given the results of a study, determining the probability that the true effect of an intervention is at least as great as some minimum worthwhile effect.
P values are widely used to convey the probability of observed effects arising by chance if there truly is no effect. By convention, P values less than 0.05 are interpreted as being "statistically significant."


CONCLUSIONS
Statistical significance is often confused with clinical significance.
A different probability could be reported, a probability I call a Q value. A Q value is the probability that the true effect of an intervention is at least as great as some minimum worthwhile effect. Q values are calculated in a manner analogous to that used for P values, except that the null hypothesis becomes a minimum worthwhile effect instead of no effect. Q values encourage researchers and clinicians to be explicit about what they think a worthwhile effect is and could help shift the focus of study interpretation away from arbitrary statistical conventions.
Froehlich
G W
GW
VA Outcomes Group, Department of Veterans Affairs Medical Center, White River Junction, Vt., USA. gregory.froelich@hitchcock.org
D002986:Clinical Trials as Topic; D016001:Confidence Intervals; D019317:Evidence-Based Medicine; D015233:Models, Statistical; D010818:Practice Patterns, Physicians'; D016896:Treatment Outcome; D014481:United States