'Any Test' Reliable Change Index Calculator

This tool can be used to calculate reliable change for ANY test by entering specific test-retest reliability values from published sources/test manuals. Our main RCI page includes many common tests with reliability values and practice effects already included- for anything else, you can use this calculator.

How to use this calculator:

Enter test/subtest name and select score type (Standard Score with SD=15, Scaled Score with SD=3, or T Score with SD=10).
Enter the test-retest reliability coefficient (r₁₂) from the test manual or other validation studies. This is the correlation between Time 1 and Time 2, not internal consistency (Cronbach's α).
Enter your patient's first (baseline) and second (retest) test scores.
Optional: Click "Add Practice Effect Scores" and enter normative means from the test manual or other published validation studies for practice-adjusted calculations.
Click "Add Another Test" to compare multiple measures.
Click "Calculate" to see results using three different methods.