Hela boken - SOM-institutet - Göteborgs universitet

A reaffirmation of public opinion
Table 1
Correlations Between Aggregate Opinion Measures Across Time
Lag 1 Lag 1 Lag of Two Lag of Three
(Unweighted) (Weighted) Years Years
Pct Pro .96 96 .91 .83
Pct Con .95 .95 .91 .82
Balance Measure .96 .96 .91 .83
Issue Intensity .92 .93 .86 .80
Pro Intensity .92 .94 .89 .84
Con Intensity .90 .90 .86 .83
Mean .95 .96 .91 .83
Percent Don’t Know .65 .65 .44 .51
Percent Opinionation .87 .87 .84 .78
Number of Cases 245 73 190 150
Comment: Entries are positive product moment correlations between facets of public opinion
measured at different times (autocorrelations).
While the correlations in Table 1 are based on a large number of cases (245), some
of the item pairs appear in several surveys, while others may have appeared only
once in successive years. Only the proposal to “reduce the size of the public sector”
appeared in all 15 surveys. So, it could be argued, these correlations are as large as
they are because of certain stable items being asked in many years and thus such
items may have a disproportionate effect. Therefore, the analysis was repeated
so that each issue was weighted the same. For example, If an issue was asked in
successive years only once, it was weighted at 1.0. If an issue appeared in four sets of
successive years, each instance of that issue was weighted at 0.25. When the analysis
was repeated, with the weighting procedure in effect, the results were essentially
unchanged (see column 2 in Table 1).
Columns 3 and 4 show what happens when the lag is increased from one year to
two and three years. If aggregate public opinion is stable and slowly evolving, one
would expect the two year lag to yield a slightly lower correlation than the one-year
lag, and for the three year lag to produce a slightly lower correlation than the two
year lag. That is exactly what happens. For the balance measure, the correlations
were +.96 for the one year lag, +.91 for the two year lag, and +.83 for the three year
lag. The comparable correlations for issue intensity were +.92, +.86, and +.80 for
the one, two, and three year lags, respectively. Time, as such, cannot cause anything
or any change to occur, but it does give greater allowance for other things to occur
in a dynamic system. The picture then is of public opinion as a stable but evolving
force. The only exception to this type of trend was in the percentage leaving the
item blank where the three year lag yields a somewhat higher correlation than
the two year lag.
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