Just an idea for future developments. Many participants have said that they started answering to a survey, but had to put the phone away for some minutes. After they opened the app again, all of their previous answers were erased and they had to start answering from the scratch. Some of them said, they did not even close the app, they just locked their phone screens, but still everything was gone. It would be very convenient for respondents if their previous answers would be saved and they can continue answering where they left off.