title: ["P" as in Program Package. About torturing data and significant "fishing expeditions"].
abstract: For the study of prognostic factors, the medical researchers have access to a number of advanced statistical techniques available in standard program packages. A tradition has developed where survival or time to relapse is analysed on the basis of statistical materials with few patients but a large number of possible explanatory variables. In statistical "fishing expeditions" the p-values are used to sort out potentially useful prognostic variables. Since the number of observations is small, all relevant prognostic factors do not give statistical significance. Since a large number of variables are tested there is a considerable risk for spurious significances. It is not enough to show that a prognostic factor seems to be efficient in the patient group where it was first found. The result must be verified in further studies of independent groups of similar patients.
mesh_terms: D016001:Confidence Intervals; D003627:Data Interpretation, Statistical; D006801:Humans; D011237:Predictive Value of Tests; D011379:Prognosis; D015203:Reproducibility of Results; D013223:Statistics as Topic
vernacular_title: Med P:n som i programpaket. Om datatortyr och signifikansfiskeri.