Note: * Precertification of denosumab (Prolia and Xgeva) is required of all Aetna participating providers and members in applicable plan designs. For precertification of denosumab (Prolia and Xgeva), call (866) 503-0857, or fax (866) 267-3277.
Observer Expectancy Effect. The observer expectancy effect, also called the experimenter expectancy effect, is a phenomenon that can occur when a researcherâs beliefs or expectations cause him or her to unconsciously influence the participants of an experiment. In order to conserve the internal validity of an experiment, researchers can use a double-blind experimental design.
Interaction Effects. An interaction effect is a change in the simple main effect of one variable over levels of the second. An A X B or A BY B interaction is a change in the simple main effect of B over levels of A or the change in the simple main effect of A over levels of B. In either case the cell means cannot be modeled simply by knowing the size of the main effects.