The P value of .05 has once again been questioned as a threshold for clinical significance in medical research, this time in a commentary that offers a way to ease toward more relevant alternatives.
"The problem with P values is that if you take their exact definition, what they convey is not something that any clinician would ever be interested in, with very rare exceptions," according to John PA Ioannidis, MD, DSc, Stanford University, California.
The P value, he told theheart.org | Medscape Cardiology, "is a bit of a ritual that has been embedded across the literature. It's misleading and wrong. We just have to get rid of it."
Indeed, scientists and journals should replace the P value threshold for significance, typically P < .05, with one tenth the magnitude, Ioannidis argues in a viewpoint published March 22 in JAMA.
The new P = .005 standard would be a temporary fix until the field more consistently adopts and ingrains a more clinically relevant statistical test, or several depending on the type of analysis, he proposes.
That P values are currently "misinterpreted, overtrusted, and misused" means that a research finding within the .05 standard "is wrongly equated with a finding or an outcome (eg, an association or a treatment effect) being true, valid, and worth acting on," Ioannidis writes.
