Dr. Johnson is investigating test-retest reliability in his study on heart rate variability. This type of reliability assesses the consistency of a measure across time. In this context, test-retest reliability involves administering the same measurement of heart rate variability to the same subjects on two different occasions and then comparing the results. High test-retest reliability indicates that the measurement is stable over time, which is crucial for ensuring that the findings are not due to fluctuations or changes in the subjects' conditions.
In studies examining physiological measures like heart rate variability, researchers often seek to establish that their measurement method produces consistent results, thus validating the reliability of those measures over repeated tests. This aspect is vital when conducting research in psychology and other fields where physiological responses may fluctuate.
The other types of reliability mentioned, such as internal reliability, inter-rater reliability, and split-half reliability, focus on different aspects of measurement consistency. Internal reliability assesses the consistency of results across items within a test, inter-rater reliability evaluates the agreement between different observers or raters, and split-half reliability looks at the consistency of results between two halves of the same test. However, these concepts do not directly pertain to the repeated measures aspect central to the study of test-retest reliability in Dr. Johnson