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Table 1 Assessment issues with DS and other intellectual disabilities

From: Development and validation of the Arizona Cognitive Test Battery for Down syndrome

Challenge Solutions
Floor effects Use measures with graded difficulty measures that are error based. The standard scores on many measures do not provide a range at the lower end. Use measures with a low floor or use raw scores controlling for age
Language ability Focus on tests that are primarily nonverbal, with nonverbal responses, adapt instructions for the population
Assessment variability due to behavior and cooperation Include careful interview of caregivers (or teachers), experimenter ratings of behavior and cooperation on each test, multiple tests included as a performance check
Sensitivity of the measures to detect effects Choose measures with continuous normally distributed outcomes; measures should demonstrate concurrent validity and show age-related change. Measures show differences between populations or have been documented to be impaired in the past literature
Flexibility of use Choose measures that are easily adaptable across cultures, and that can be used in home or lab-based assessment
Applicability across a range of ages Choose measures with graded levels of difficulty
Reproducibility, lack of validation of measures in populations with developmental disabilities Use specially validated tests, collect test-retest reliability estimates that are sample-specific