The impact of incentives and interview methods on response quantity and quality in diary- and booklet-based surveys

This paper investigates the impact on response quantity and quality of a diaryand bookletbased survey of using different interview methods and lottery prizes. In addition to a conventional questionnaire the survey included time-diaries for household members and a booklet for recording the previous month’s spending by the household. The respondents could choose to use either CATI (Computer-Assisted Telephone Interviewing) or web-based CAPI (Computer-Assisted Personal Interviewing) for the different parts of the survey. Lottery prizes varied during the survey period, and the prizes were doubled if they had used only the CAPI method. The response rate was significantly affected by the size of the lottery prizes, and the doubling of these prizes for using the web had a high impact on the number of respondents choosing this method. The response quality did not vary systematically with the size of the lottery prizes per se, but the quality did increase as a result of the impact on the number of web interviews, because this method was found to yield a significantly higher quality for the diary, booklet and questionnaire information.