Replication, statistical consistency, and publication bias

Scientific methods of investigation offer systematic ways to gather information about the world; and in the field of psychology application of such methods should lead to a better understanding of human behavior. Instead, recent reports in psychological science have used apparently scientific methods to report strong evidence for unbelievable claims such as precognition. To try to resolve the apparent conflict between unbelievable claims and the scientific method many researchers turn to empirical replication to reveal the truth. Such an approach relies on the belief that true phenomena can be successfully demonstrated in well-designed experiments, and the ability to reliably reproduce an experimental outcome is widely considered the gold standard of scientific investigations. Unfortunately, this view is incorrect; and misunderstandings about replication contribute to the conflicts in psychological science. Because experimental effects in psychology are measured by statistics, there should almost always be some variability in the reported outcomes. An absence of such variability actually indicates that experimental replications are invalid, perhaps because of a bias to suppress contrary findings or because the experiments were run improperly. Recent investigations have demonstrated how to identify evidence of such invalid experiment sets and noted its appearance for prominent findings in experimental psychology. The present manuscript explores those investigative methods by using computer simulations to demonstrate their properties and limitations. The methods are shown to be a check on the statistical consistency of a set of experiments by comparing the reported power of the experiments with the reported frequency of statistical significance. Overall, the methods are extremely conservative about reporting inconsistency when experiments are run properly and reported fully. The manuscript also considers how to improve scientific practice to avoid inconsistency, and discusses criticisms of the investigative method. (C) 2013 Elsevier Inc. All rights reserved.