Fig. 2
Cross-sectional agreement between the measures from the shortened gait and TUG tests and the reference variant. (A) agreement for gait speed; (B) agreement for TUG test duration (TTD). Agreement is reported separately for the first (T0, left) and the second (T1, right) assessment session. Upper plots in panels A and B are Bland-Altman plots of the difference between measures from the shortened and the reference test (y-axis) as a function of the reference test measures (x-axis). Reference test: the test is repeated five times, metrics collected from each repetition and the person’s measure is the median of five metrics. Comparison (new, shortened) test: the test is repeated three times, the first repetition is discarded, metrics are collected from the second and third repetition, and the person’s measure is the mean of two metrics (i.e. Trial2 − 3 measures). Continuous horizontal line: bias (i.e. mean difference between measures); horizontal dashed lines: limits of agreement. Lower plots in panels A and B show the absolute percentage error (APE, y-axis) of the measures from the reduced tests as a function of the measures from the reference tests (x-axis). Lower horizontal dashed line: mean APE (label not shown for graphical reasons). Upper horizontal dashed line: APE 95th percentile. Each dot marks a person’s measure