Table 4.

Levels of engagement measured in microrandomized trials of mobile health (mHealth) interventions.

Source			Little e					Big E
			Yes or no		Example		Yes or no			Example
Evaluate effect of intervention components
	Aguilera et al [23], 2021	Yes		Response rates to daily mood rating SMS		No			N/Aa
	Battalio et al [24], 2021	Yes		If end-of-day logs for smoking are completed		No			N/A
	Goldstein et al [26], 2021	Yes		Percentage of interventions accessed		No			N/A
	Klasnja et al [27], 2021	Yes		Adherence to wearing the FitBit		No			N/A
	Klasnja et al [28], 2019	Yes		Adherence to activity tracker		No			N/A
	Kramer et al [29], 2020	Yes		Whether participants responded to first message of the chatbot in an intervention conversation		No			N/A
	Latham [30], 2021b	Yes		Percentage of sleep diaries completed		Yes			Self-reported adherence to intervention prompt’s suggestion
	Jeganathan et al [31], 2022	Yes		Nonadherence with recommendations for watch wear time		No			N/A
	Spruijt-Metz et al [33], 2022	Yes		Time since FitBit was last worn		No			N/A
	Wang et al [34], 2022	Yes		Proportion of days that daily step/sleep minutes were provided within a week		No			N/A
	Dowling et al [35], 2022	Yes		EMAc compliance		No			N/A
	Rodda et al [36], 2022	Yes		EMA compliance		No			N/A
Evaluate strategies to improve engagement
	Bell et al [22], 2020	Yes		Whether participants opened the intervention app in the hour after microrandomization		No			N/A
	Bidargaddi et al [37], 2018	No		N/A		Yes			Whether participants performed the self-monitoring intervention activity
	Nahum-Shani et al [38], 2021	No		N/A		Yes			Whether participants engaged in self-regulatory activities 1 h after randomization
	Nordby et al [39], 2022	Yes		Minutes spent on the intervention		Yes			Self-reported frequency of practicing coping strategies taught
Evaluate feasibility and acceptability of intervention
	Militello et al [40], 2022	Yes		Opening the application		Yes			Self-reported engagement with mindfulness exercises 24 hours after randomization
	Yang et al [41], 2022	Yes		Percentage of EMAs completed		Yes			Percentage of prompted strategies completed
Describing engagement
	Hoel et al [42], 2022	Yes		Proportion of submitted and nonblank logs		No			N/A
	Valle et al [43], 2020	Yes		Proportion of intervention messages viewed before end of day		No			N/A

^aN/A: not applicable.

^bThis study was also designed to evaluate the feasibility and acceptability of its mHealth intervention.

^cEMA: ecological momentary assessment.