Final answer:
The Minimum Detectable Change (MDC) and the Minimal Clinically Important Difference (MCID) are valid for data measured on interval scales and ratio scales where differences or ratios can be quantitatively assessed.
Step-by-step explanation:
The Minimum Detectable Change (MDC) and Minimal Clinically Important Difference (MCID) are concepts used to describe the amount of change in a variable that must be achieved to ensure that the change is not the result of measurement error (MDC) or is meaningful and beneficial from a clinical perspective (MCID). These are often used in scales and measurements relevant to health outcomes and physical therapies. When we refer to the type of point scale these concepts are valid for, we are considering the level of measurement for the data collected.
Data measured on an ordinal scale can be ordered but the differences between data points cannot be exactly measured, which means that while we could detect a change, we can't quantify the exact magnitude of change with certainty. On the other hand, data on an interval scale or a ratio scale not only can be ordered but also allow us to precisely measure the difference or the ratio between data points, respectively. Since the MDC and MCID require the ability to measure differences with precision, they are valid for interval and ratio scales.