摘要：The non-response in a survey can lead to severe bias. In order to manage this problem, it
is usual to make a second survey by a sample of non-respondent. This allows us to test if there
is a significant difference in the key variables of the survey between respondents and non-
respondents and, if yes, to take it into account. But, the risk is great to introduce another bias
depending on the mode (mail vs phone) of survey.
The KOF industrial economics group is exploring for many years the innovation behaviour
of Swiss firms using a mail survey addressed to almost 6600 panel firms of the industrial,
construction and service sector. We use since some years the data of a second survey by non-
respondents to correct non-response bias. Contrarily to the first survey, this one is made by
phone. One can suspect that the personal interaction with the person(s) calling may be
introducing another bias. In order to investigate this question, in the case of the ETH Zurich’s
innovation 2002 survey, we decided next to the regular non-respondent-phone-survey, to
conduct a similar phone survey by a subsample of the respondent-group. Thus, we dispose of
data for the same variables coming from the two modes of survey and allowing us to show if
there is a difference or not in the response behaviour. We use different statistical approaches to
investigate this issue, considering χ2
-test and Logit models. Our results show that data
collection method may influence the response.
