The purpose of this discussion is to alert you to common difficulties when comparisons are made between the ACLs and other scales. There are rules for qualifying for each type and rules about the application of the scores:
- Nominal scales: collect lists of things that are used to name or label things. The behaviors used to diagnose mental disorders and the items used to identify a diminished mental status are commonly used nominal scales.
Note: Lengthy nominal scales that have a lot of items are deceptive because nominal scales cannot measure improvement or decline. The assumption that more numbers can measure change better is true for ordinal scales but not nominal scales.
- Ordinal scales: list things in order or in a hierarchy, which is why they can measure improvements or declines.
Note: Lengthy ordinal scales do measure improvement and decline better than shorter ordinal scales because they are more sensitive to change. The 25 ACL modes are the longest ordinal scale for measuring cognitive ability to function below normal.
- Interval scales: list things with even qualities or quantities between each item. The statistics used to predict assume that an interval scale is used.
The ACL scale has known jumps that disqualify it as an interval scale, and the statistics that assume intervals should not be used.
Note: The problem is that human beings do not change or behave in even intervals naturally.
- Ratio scales: require a zero, i.e. dead? The ratio scales are used to measure material objects, such as rulers.