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

330 ASKING QUESTIONS
discussion as to how many points and what kinds of scale labels
(anchors) make up the most effective measurement tool. Each scale
has variations, some more reliable than others.
Even-numbered scales (4-point or 6-point scales) can more
effectively discriminate between satisfied or dissatisfied customers
because there is not a neutral option. Carefully consider whether a
clear division between positive and negative responses is necessary
or whether a midpoint will be more appropriate. Although scales
without midpoints are often used when measuring personality characteristics,
our general bias is toward odd-numbered scales.
The number of points for your scale should be determined by
how you intend to use the data. Although 7- to 9-point scales may
seem to gather more discriminating information, there is debate as
to whether respondents actually discriminate carefully enough
when filling out a questionnaire to make these scales valuable, particularly
in phone interviews. Many researchers nevertheless collect
such information using scales with many points, even if in the
end they summarize that information as simply “disagree,” “neutral,”
and “agree.”
Once the number of points on a scale has been decided, determine
the labels for each scale point. With scales with few points,
every point can be labeled. Other researchers prefer to label or define
only the end points. This provides a scale with equal-appearing
intervals between each scale point, with only numbers labeling the
intervals. This format is particularly common with large scales.
How Many Response Categories Should I Have?
No more than necessary. Recall from Chapter Nine that a typical
question about marital status might ask a person to check a box
to indicate whether he or she is (1) Never married, (2) Divorced,
(3) Married, (4) Separated, or (5) Widowed. Unless marriage is a
focus of the study, distinguishing among these categories will not be
particularly useful. If such a question is primarily asked to distin-