President Obama’s chances of winning the Electoral College improved slightly on Tuesday, to 69.0 percent from 66.9 percent one day earlier, according to the FiveThirtyEight forecast model. The change was because of new government data showing faster growth in personal income, one of the seven economic data series that our forecast model uses.
The sluggish growth in personal income — it was previously reported as having increased essentially no faster than the growth rate in the population for much of Mr. Obama’s term — had been one of the better reasons to conclude that his re-election bid was in a great deal of trouble. Measures of personal income are popular in the forecast models of elections produced by political scientists and economists — in part because they potentially do a good job of measuring the economy as it is experienced by voters, and in part because the correlation between personal income and election outcomes has been reasonably high in the past.
There are also reasons to be wary of the personal income data. It is extremely noisy, for instance — with large fluctuations from month to month and from quarter to quarter — and it frequently undergoes significant revisions.
On Tuesday, however, those revisions worked to Mr. Obama’s benefit. Data from recent previous months was revised upward to show more income growth. And the latest print of the data, describing the income growth in June, was also fairly strong.