Editorial for: Therapeutic approaches for working with people in later life.

A central aim of science is to discover regularities in nature. If a claimed discovery is true, independent researchers should be able to conduct a similar investigation and reach similar conclusions. A replication attempt is testing the same research question as a prior investigation with independent evidence, whether the evidence is a new data collection or existing secondary data that was not used in the prior investigation. Across several prior replication studies in the social and behavioral sciences totaling hundreds of replication attempts, approximately half of well-powered replication studies provided statistically significant evidence in the same direction as an original finding. Moreover, observed effect sizes in replication studies were about half as large as effect sizes in original studies on average. Similar results have been observed in other fields, such as preclinical cancer biology. Popular explanations for the low observed replication success rates include underreporting of negative or inconclusive evidence for claims; high sampling error from small samples and measurement error due to unreliable measures, coupled with a statistical threshold ( < .05) that serves as a publication filter; low rigor and quality control in research design and measurement; and questionable research practices that inflate the likelihood of obtaining positive outcomes. These factors are compounded by a research culture that rewards novel and “interesting” findings and discourages error correction. Replication failures are not necessarily due to the original findings having low credibility. Low replication rates can also be due to false negatives, poorly designed replications, selecting only positive results for replication, and differences between original and replication studies that are initially perceived as unimportant. More broadly, there are conceptual challenges in deciding what is a replication of a prior finding and how to assess whether a replication attempt succeeded. Attempting replications provides a grounded context to wrestle with those challenges.