Geospatial map of participant homes (n = 100) in a study of real-time adherence monitoring using devices that transmit bottle openings via cellular phone networks.

Panel A shows connectivity failure rates for devices with general packet radio service (GPRS) network compatibility only. Panel B shows connectivity failure rates for devices with general packet radio service and short message service (GPRS+SMS) compatibilities. Green markers represent households with no history of network failures; yellow markers for households with 0–1 failures/28 days; red markers for households with >1 failure/28 days.