This tool is designed to help you assess whether your client has shown statistically reliable changes (improvements or declines) in their cognitive test scores between two assessment dates. This calculator does not include all possible cognitive tests, if you have others that you wish to do reliable change calculations on and you have test-retest reliability data (from the manual or other published source), you can do so using our 'custom' RCI calculator on the analysis subpage, above. Please note that the WISC5 calculation is based on the Australia/New Zealand version, which may have poorer validity for use outside of that region.