If an instrument is consistent in measurement but does not accurately measure what it was designed for, the instrument is considered:

When an instrument is described as consistent in measurement but fails to accurately capture what it was intended to measure, it indicates that the instrument has reliability without validity. Reliability refers to the degree to which an instrument produces stable and consistent results over repeated trials or measurements. In this case, the instrument is able to give consistent results, which showcases its reliability. However, validity pertains to the ability of the instrument to measure what it claims to measure. Since the instrument does not accurately assess its intended purpose, it is deemed invalid.

This distinction emphasizes the importance of both reliability and validity in appraisal and measurement instruments. An instrument can be reliable—yielding the same results under the same conditions—yet still lack validity if it does not measure the right construct. Therefore, drawing from these definitions and the relationship between reliability and validity leads to the conclusion that the correct categorization for the situation described is that of being invalid but reliable.