A principle of derivation and decisions based on statistical tests and effect sizes

This article in Chapter 1 deals with deriving predictions from one psychological hy-pothesis meant to be examined as aggregate hypothesis. During derivation, two additio-nal criteria, adequacy and exhaustiveness, should be attended to. Adequacy refers to the direction of effects specified by the psychological hypothesis, and exhaustiveness to the number of partial predictions which the psychogical hypothesis contains. Secondly, be-cause of the lack of a logical form of judgement a strategy of decision and evaluation is outlined which allows to take into account more systematically measures of effct sizes in the evaluation of the psychological prediction and about the psychological hypothesis to be examined (Chapter 2). If an experiment is planned properly, there are only few pat-terns of results possible, where each pattern consists of the result of a statstical test and a value of the effect size. These possible patterns of results are tabulated, and each pat-tern is classified with respect to the meaning it bears for the psychological prediction derived from a psychological hypothesis. Under certain premises the evaluation of the psychological prediction can be transfered to the psychological hypothesis. - Whereas the derivation of predictions is largely based on deductive considerations, the evaluation of predictions and of the psychological hypothesis is a matter of inductive reasoning which never is as strict as deductive reansoning. Thus, the inductive reasoning part lea-ves more degrees of freedom the the researcher.