STEP 7:FIND OUT HOW CONSISTENT SCORES TEND TO BE
Information for this step and the next will again be found in the technical material for the instrument. First, look for a section on “Reliability,” or sections on “Test-retest Reliability,” “Internal Consistency,” and “Interrater Agreement.”
Basically, reliability is consistency. There are three aspects to reliability:
• homogeneity within scales,
• agreement within rater groups, and
• stability over time.
Without evidence of reliability, we do not know whether the items and scales of an instrument are good enough to hold up even under stable conditions with similar raters. In other words, we do not know whether items that are grouped together in a scale are measuring the same competency (homogeneity ...