Table 2.

Sample characteristics (N=450).

Variables		Value, n (%)
Gender
	Male	180 (40.0)
	Female	270 (60.0)
Age (years)
	<20	5 (1.1)
	20-29	157 (34.9)
	30-39	157 (34.9)
	40-49	82 (18.3)
	50-59	36 (8.0)
	≥60	13 (2.9)
Annual household income (US $)
	<25,000	72 (16.0)
	25,000-49,999	115 (25.5)
	50,000-74,999	112 (24.8)
	75,000-99,999	75 (16.6)
	≥100,000	76 (16.8)
Education
	Less than high school	22 (4.9)
	High school graduate	45 (10.0)
	Some college	77 (17.1)
	2-year degree	35 (7.7)
	Bachelor’s degree	257 (57.1)
	Graduate degree	14 (3.1)
Employment status
	Employed full time	311 (69.1)
	Employed part time	73 (16.3)
	Unemployed	33 (7.4)
	Retired	10 (2.2)
	Student	23 (5.1)
Race and ethnicity
	White	301 (66.9)
	African American	51 (11.4)
	Asian	27 (6.0)
	Hispanic	66 (14.6)
	Mixed	5 (1.1)
Experience with mobile devices (eg, phone, tablets)
	Slightly experienced	8 (1.7)
	Moderately experienced	77 (17.1)
	Very experienced	145 (32.3)
	Extremely experienced	220 (48.9)
Experience with PHDsa
	Slightly experienced	40 (8.9)
	Moderately experienced	134 (29.7)
	Very experienced	172 (38.3)
	Extremely experienced	104 (23.1)
Frequency of use
	Rarely	8 (1.7)
	Monthly	44 (9.7)
	Weekly	119 (26.6)
	Daily	279 (62.0)
Length of use
	<6 months	84 (18.6)
	6 months to 1 year	131 (29.1)
	1-2 years	110 (24.6)
	>2 years	125 (27.7)
PHDs used by participants
	Fitbit	176 (39.1)
	Apple Watch	90 (20.0)
	Samsung Galaxy Fit	81 (18.0)
	FitTech Smart Watches	58 (12.8)
	Garmin Fitness Watches	27 (6.0)
	Other Smart Fitness Trackers	18 (3.9)
Purpose of use
	Controlling fitness and diet	203 (45.1)
	Monitoring blood pressure and checking the cholesterol level	122 (27.1)
	Controlling or quitting smoking	54 (12.0)
	Monitoring chronic diseases (eg, diabetes and heart disease)	45 (10.0)
	Controlling depression or anxiety	26 (5.8)

^aPHD: personal health device.