Assessing exposure factors in the smartphone generation: Design and evaluation of a smartphone app that collects use patterns of cosmetics and household chemicals

The development costs for smartphone app and paper questionnaire were comparable with 15′000 and 13′500 US-$, respectively. The cost efficiency for the paper questionnaire was much better than for the app, but model calculations show that the cost efficiency of the app improves considerably with adequate promotion and for larger surveys, especially for those with regular repetitions. Barcode scanning of consumer products by app saved time and effort of the participants and enhanced reliability. The app was able to attract the attention of younger adults between 20 and 40 years old: Thus, the limited representativity for younger age groups that sometimes is observed for paper-based surveys may be enhanced by including the option to use an app in a mixed-mode survey.