Asking Questions - The Definitive Guide To Questionnaire Design ...

162 ASKING QUESTIONS
least desirable. If the more desirable categories come first, the
respondent might choose one of those categories without waiting
to hear the entire set of response categories.
Using Numerical Rating Scales
If you wish to go to a rating scale with more than seven points, it
can sometimes be helpful to use a visual aid or device that employs
something beyond the use of words. Most of the examples we will
present here are variations on a fairly simple theme. The basic strategy
is to use a numerical scale running from 0 or 1 to some number
and give English value equivalents to the lowest and the highest
categories as anchoring points for the ends of the scales. Figure 5.2
gives one example of this method. The figure shows the question as
it appears in the questionnaire seen only by the interviewer and
as it appears on the card seen by the respondent. If a series of substantive
opinion questions is to be asked, and if the same scale can
be used for all questions, the interviewer can read the anchoring
points to the respondent for each separate question.
Odd or Even?
A much-debated point is whether to give respondents an odd or
even number of response categories. We believe you must always
provide for an odd number of categories, in order to reserve a middle
or indifferent point for respondents who insist on taking middle
positions or who are undecided or indifferent about the two ends of
the continuum. The difference lies in whether you explicitly give
respondents the middle option or whether you give them an even
number of categories and conceal the middle position from them.
If presented with an even number of response categories,
respondents who feel in the middle must “lean” toward one end or
the other of the distribution unless they are firm about their middle
position. The arguments for using even or odd numbers of categories
are similar to those described in Chapter Four in the section