Ease of articulation: A replication

Researchers, as well as the lay public and the popular press, have become increasingly concerned about the lack of reproducibility of research findings. Despite this concern, research has shown that replications of previously published work comprise a very small proportion of published studies. Moreover, there are fewer published direct replications of research studies by independent investigators, and this type of replication is much less likely to confirm the results of the original research than are replications by the original investigator or conceptual replications. A search of the communication disorders research literature reveals that direct replications by independent investigators are virtually non-existent. The purpose of this project was to describe the major issues related to research reproducibility and report the results of a direct replication of a study by Locke (1972) regarding ease of articulation. Two methods for rating ease of articulation were employed. We were able to reproduce the results of the original study for the first method, obtaining a moderate positive correlation between our rankings of phoneme difficulty and Locke's rankings. We obtained a very high positive correlation between our phoneme rankings and rankings obtained in the original study for the second method. Moreover, we found a higher correlation between difficulty rankings and order of speech sound acquisition for American English than was found in the original study. Direct replication is not necessary for all studies in communication disorders, but should be considered for high impact studies, treatment studies, and those that provide data to support models and theories.

The reader will be able to: (1) describe the major concerns related to the replicability of research findings; (2) describe the status of research replications in communication disorders; (3) describe how ease of articulation may relate to the order of speech sound acquisition in children; (4) list some types/areas of research that might be candidates for replication in the field of communication disorders.