GROUPS – The index is dramatically different across population groups – 51 among Democrats, for instance, rising to 73 among independents and 82 among Republicans. Similarly, among registered voters who currently favor Democrats for Congress, it's 53; among those who favor Republicans, it's 84. Underscoring the risk to all incumbents, the Frustration Index among swing voters – likely voters who say their party preference may change – also is quite high, 73.
The gaps extend to broader views; among people who say the country's headed in the right direction, the index is 46. Among those who say it's seriously off on the wrong track, it's 81. Among those who say the economy's in good shape, 24; poor shape, 82. And among those who approve of Barack Obama's job performance it's 47; among disapprovers, 91.
It's important to note that, in election terms, the index is "postdictive," to use Edward R. Tufte's term in his 1974 classic, "Data Analysis for Politics and Policy." It does not predict the future, in which other, unforeseen factors can come into play.
There's a particular reason for caution this year: The divergence between public views of current economic conditions, which are dreadful; and expectations of the economy's future, which have improved lately, to their best in six years, as we reported in mid-May.
If we swap out ratings of the current economy in the Frustration Index and replace them with economic expectations, the index is lower, 58 not 67, an unusually large gap between the two approaches in available data.
Both versions – current economic sentiment and economic expectations – correlate, retrospectively, with incumbent re-election and with a president's party's House gains or losses. The divergence this year makes economic expectations a significant wildcard to keep in mind as the midterm elections approach.
A note on correlations: The individual items in the Frustration Index correlate with one another at a range from .54 (presidential approval and support for incumbents) to .92 (presidential approval and satisfaction with how the federal government is working). (A correlation is a measure of data congruence, in which 1 means the data move perfectly in tandem, -1 means they move perfectly in opposition and 0 means they move independently.) The Cronbach's Alpha for the index is .88, indicating its components measure the same underlying construct. The index correlates with views that the country's on the wrong track at .89; its estimated values in midterm elections since 1994 (note the small number of cases) correlate with losses by House incumbents at .81 and with losses for the president's party at .72. Index numbers for elections were estimated with a formula obtained by regressing available index numbers on another index, created by combining presidential approval and ABC's weekly Consumer Comfort Index. The indices correlate at .99.
A full list of available index points follows. Those given with dates were assembled from existing data; those marked as election data points were estimated via regression analysis.