Replication and Reproducibility in Psychological, Medical and other Sciences

Abstract

As there are no universal constants in psychological, medical and economic sciences, only constructive-phenomenon replications are meaningful. Yet, psychologists continue to perform direct replications, as evidenced by recent preregistered multilab attempts at exact replications of the ego depletion effect. Statistics are driving the replication movement into a ditch because of an overemphasis on the determination of statistical magnitude of effects while ignoring commonsense magnitude and other criteria for evaluating phenomena’s validity, reliability, and viability. The nature of the human mind and the variability of psychological phenomena pose difficult challenges for the scientific method and insurmountable obstacles for precise replications in psychological sciences. The situation is no better in medical and economic sciences. The interaction effect of person (genetics) and environment (lifestyle) calls for constructive replications to determine, for example, drugs’ efficacy as a function of group and individual differences. The vaccine-vaccination paradox is an interesting case because psychological and medical sciences meet at this intersection. In all fields, science advances by theory building and model expansion, not by replication tests of statistical hypotheses. Rigorous logical and theoretical analysis always precedes and guides good empirical tests. The nonexistence of an effect is not viable if it can withstand rigorous logical and theoretical analyses. Empirical studies are mainly evaluated for their theoretical relevance and importance, not their success or failure to exactly reproduce the original findings.