Developmental psychologists should care about measurement precision

In a wide ranging article in this journal, Byers-Heinlein et al. (2022) make a persuasive case for paying close attention to reliability in developmental research. They focus on measurement reliability, which indexes how well individuals can be ranked across repeated measurements. We highlight the importance of measurement precision as a complement to understanding measurement reliability. We describe how this more absolute type of reliability can be quantified by the within-participant standard deviation across trials, also known as the standard error of measurement (SEM). We outline how reporting and understanding measurement precision can play a key role in achieving the 'six solutions' for improving reliability in developmental research offered by Byers-Heinlein et al.