The reproducibility of data has most frequently been discussed with respect to experimental research in social and cognitive psychology. This article addresses how the reliability and validity of an observational study can be confirmed and whether an observational study can be replicated in a natural setting, as well as in an experimental (or semi-experimental) setting in developmental psychology. In a natural setting, the subject’s cultural and historical background, as well as immediate factors, including the physical environment and social context, may need to be considered to understand individual behaviors and social interactions among two or more people. Therefore, it can be quite difficult to perform a meaningful replication study. Researchers in the various domains of psychology should employ various measures, including the use of alternative procedures other than a replication study, in order to ensure the reliability and validity of their findings.
