For many years, Business Tendency Surveys on the basis of mailing suffer from an erosion of the response rate. To counter this problem, there are traditional methods as limitation of the number of questions, improvement of the design of the questionnaire, intensified recalls by mail or...

In order to correct the bias due to unit non-response for the KOF ETH Zurich's business (mail) surveys, we usually use the results of a second (phone) survey by the non-respondents. Taking the case of the survey 2000 on "Organization and Information Technologies" in the Swiss economy, we...