Recruit beyond tech-savvy volunteers by including varied ages, jobs, locales, and device capabilities. Provide clear expectations, multilingual materials, and accessible support. Balance sample diversity with analytical feasibility, and avoid excluding lower-spec phones that mirror many customers’ realities, even if logging rates need adaptation and lighter configurations.
Use stable SDKs with transparent permissions, background tolerances, and fallback queues. On Android, anticipate foreground service limits and battery optimizations; on iOS, respect background refresh windows and motion permissions. Encrypt at rest and in transit, verify uploads, monitor missingness dashboards, and fail safely when connectivity drops unexpectedly.
Schedule prompts with humane bounds: quiet hours, commute windows, and daily caps. Blend randomization with context cues like recent unlocks, stationary states, or low interaction. Allow snooze and skip without penalty, and adapt frequency based on response patterns to protect goodwill while preserving analytical coverage.
Strip identifiers, hash or tokenize where possible, and aggregate sensitive features locally before upload. Sample sparsely, round timestamps, and blur locations to neighborhoods. Adopt data classification tiers, justify each field, and document trade-offs, ensuring no one can reconstruct intimate routines from combined streams or careless joins.
Replace one-time paperwork with plain-language screens, reminders, and choices participants can revisit. Explain sensors, triggers, risks, benefits, and contacts. Provide pause, delete, and feedback controls in-app, and notify transparently about updates so trust deepens through predictable, respectful interactions rather than legalese and uncomfortable surprises.
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