The construct and concurrent validity of brief standing sway assessments in children with and without cerebral palsy

•Eyes opened and closed postural sway of children with and without CP for 30 s.•We evaluated construct and concurrent validity at shorter durations (5−25 s).•Construct validity (effect size) maintained for seven shorter duration measures.•Concurrent validity (correlation) maintained for those shorter duration measures.•Shorter durations may be more feasible for groups with difficulty standing quietly.