Examples of sensor variables with wide vs. narrow distributions. Symbols represent sample means, with error bars at ± 1 SD and arrows at the minimum and maximum values observed. 2A: Hours of use is a variable with a wide distribution in typical adult populations (open symbols, data from Bailey et al., 2013 and 201518,21) and a wide distribution in persons with stroke (closed symbols, data from Bailey et al., 201521). 2B: The use ratio, however, is a variable with a narrow distribution in typical adult and infant populations (open symbols, infant data from Trujillo-Priego et al., 201717). As is characteristic of infant data, the range from minimum to maximum is a bit wider than in adults. The wide distribution of use ratio values in the stroke population (closed symbols) includes people who have normal daily activity (the most mildly affected) and some who have almost no daily activity (the most severely affected).