Why preregistration? With preregistration, researchers stipulate their hypothesis and analysis plan in advance of data collection, tying their hands and letting the empirical chips fall where they may (Pierce, 1883).
The theoretical advantage of preregistration is that it sharpens the distinction between two complementary but separate stages of scientific inquiry: the stage of generating hypotheses (i.e., exploratory research) and the stage of testing hypotheses (i.e., confirmatory research). By respecting this distinction, researchers inoculate themselves against the pervasive effects of hindsight
bias and confirmation bias (e.g., Nuzzo, 2015). Preregistration does not prevent researchers from conducting and presenting exploratory analyses, but it does prevent them from unwittingly presenting an exploratory finding as if it had been confirmatory.