A change in score: what does it tell you?

The method

1. Calculate before interpreting

Subtract the baseline score from the follow-up score. Check which direction represents improvement and whether the protocol stayed comparable. Arithmetic tells you the size of the observed change, not its cause.

2. Ask two different threshold questions

Minimal detectable change (MDC) concerns change relative to measurement error at a stated confidence level. Minimal clinically important difference (MCID) concerns importance. They are not interchangeable. Estimates must match the instrument, population and context.

3. Do not convert a threshold into a guarantee

A change can exceed one supplied threshold without exceeding the other. That calls for a careful statement, not a forced “success” or “failure” label. This fictional exercise is not a threshold for any real patient or instrument.

WORKED EXAMPLE

Fictional Learning Measure A

Original fictional data for this learning activity
Item	Supplied fictional value
Baseline	40
Follow-up	46
MDC95	8
MCID	5

Assume higher scores are better and both measurements used the same protocol. Baseline is 40 and follow-up is 46, so observed change is +6. The supplied fictional MDC95 is 8 and MCID is 5. Six exceeds five but not eight. Describe that distinction explicitly: the change exceeds the supplied importance threshold but does not exceed the supplied detectable-change threshold. This does not prove treatment caused the change or that it matters to a particular person.

PUT IT INTO PRACTICE

Your workshop

Your answers stay in this open page unless you choose to save on this device or download. Use fictional or de-identified learning examples; leave out patient and other people’s private information.

Check the reasoning

Choose an answer to see an explanation. These are learning checks, not an official exam or score prediction.

1. What is the observed change?46 points6 points15 percent of the full scale

2. Which interpretation matches the supplied thresholds?It exceeds both thresholds.It proves the intervention worked.It exceeds MCID 5 but not MDC95 8.

Build your worksheet

ArithmeticWrite baseline, follow-up, direction and change in scale points.Two comparisonsCompare the change with each supplied threshold separately.LimitsWhat population, protocol and contextual information would you need for a real measure?

Try a changed situation

For a second fictional measure, baseline is 20, follow-up is 29, MDC95 is 7 and MCID is 10. Interpret only these supplied numbers.

Your response

Take away: Keep “how much?”, “beyond measurement error?” and “important?” as separate questions.

I have reviewed the checks and reflected on my response.

Answer both learning checks to enable your review record.

Marking reviewed records your own activity. It does not establish mastery or readiness.