Table 3 Relevant observations made concerning performance of DCT app

Adherence to app use

GPS was switched on prior and switched off after the visit

Battery consumption

Survey yields increased battery consumption, which likely reduced adherence

Energy supply

participants could not charge their Smartphone regularly due to limited access to electricity

Smartphone deficiency

corrupted memory cards; insufficient capacity of local storage; software errors (due to replicated Smartphones or Android OS, phone froze or had to be formatted)

technical experience

participants with little technical experience had to be provided with repeated training on how to use the DCT app correctly