Panel respondents give higher quality responses in later waves of survey.
The study looked at whether people in a survey change their answers over time to make the survey shorter. They analyzed data from over 10,000 people who were surveyed four times. Surprisingly, they found that people actually gave better answers in later surveys, not worse. This was also true for a smaller group of people surveyed twice. So, people don't seem to get tired of the survey and give worse answers over time.