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Donald Granberg
it changed, the change was coherent and occurred for sensible reasons. Following
this lead, Gilljam and Granberg (1995) reported an analysis of the aggregated
responses to a set of items used with three year and six year lags in the Swedish
Election Studies. They found considerable stability in several facets of public opinion,
including the most important, direction and intensity. It appears that a given
question evoked a similar pattern of responses with up to a six year lag.
In this article, I report an analysis of a large number of repeated questions used
in the SOM Studies, using the annual surveys done in 1986-2001. The questions
used here all have the same format, presenting people with a concept or proposal,
e.g. “Sweden should in the long run end its use of nuclear power [plants],” and
then people indicate whether they think it is a very good idea, a rather good idea,
neither a bad nor good idea, a rather bad idea or a very bad idea. Also, some people
leave the question blank.
The method of analysis is relatively simple and can be described rather briefly.
Imagine a two dimensional space with an x-axis and a y-axis, and assume the
unit of analysis is not the individual person but rather an issue used in two years.
For example, one of the items has to do with the idea of forbidding all forms
of pornography. A certain percentage of responses were in favor in 1987 and in
1988. Each instance like that comprises one data point with the time 1 response
determining placement on the x-axis and the time 2 response the position on
the y-axis. In addition each issue is characterized by a number of different facets
of public opinion, including percentage in favor, percentage opposed, a balance
measure, the mean response, issue intensity, pro-and anti-intensity, and percentage
of no answer responses. This enables us to check for the relative stability of different
facets of public opinion. The method used is described more fully in the article
by Gilljam and Granberg (1995).
The overall results are shown in the left-hand column of Table 1. The correlation
for the balance measure was +.96, based on 245 instances in which a question was
asked with the same wording in two successive years. The correlation using mean
values for time 1 and time 2 was essentially the same (+.95). Thus, how people
respond to a given proposal at time 1 is a very strong predictor of how a comparable
but different sample of people respond at time 2. It is practically impossible to
imagine that such a correlation would occur if there was “nothing out there.” On
the contrary, the results are entirely consistent with the notion that public opinion
in the aggregate is real and capable of being measured consistently.
While the balance measure and the mean are perhaps the most important
dimensions, the other correlations in Table 1 pertaining to intensity are also robust.
Furthermore, the results here dovetail nicely with the results reported by Gilljam
and Granberg (1985). For example, they found the 3 year lag for the balance
measure to be +.80, while here that correlation is +.83. It may also be noted that
their analysis was based on in-person interviews, while here the data are based
on mailed surveys.
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