To clarify the context of the question, we recommend repeating the reason for the impairment again in the question text:
Has the interference at your place of residence by infrastructures (e.g. highways, railroad tracks, power lines) increased, decreased or remained the same in the last 5 years?)
Question 7 was asked only of those respondents who had selected a scale value of 0 to 10 in question 6. The majority of subjects (75 %) indicated that the impairment caused by the infrastructures men-tioned in question 6 had remained the same over the past 5 years. Just over one-fifth of respondents (22 %) registered an increase in impairment and just under 3 % a decrease.
The aim of the pretest was to investigate whether the subjects had difficulties answering this question and, if so, what the difficulties were. The corresponding cognitive probes (N1-F7 and N2_F7, see Ap-pendix) were asked of the 124 subjects who were (randomly) assigned to Group 1.
About 18 % (n = 22) of the respondents stated that they found it “rather difficult” or “very difficult” to answer question 7. In most cases, this was because this (and the previous question) was a difficult topic that they had not yet dealt with sufficiently.
Some respondents (n = 5) cited as a reason that it was unclear which “impairments” they were referring to:
