Table 2.

Missing data analysis results.

Measure	Phone	Watch	Z value	t value (df)	P value
Proportion of missing data days (<8 hours)	0.03	0.54	3.920	N/Aa	<.001
Mean valid data days	23.5	22.2	N/A	0.460 (20)	.65

^aN/A: not applicable.