At
The Washington Post, Patrick J. Egan offers two graphics illustrating which poll numbers have predictive ability
16 months before the presidential election:
The relationship between presidential approval and election results 16 months later is statistically significant (at p = .04 if you’re counting) and as we would expect, slightly stronger in election years when the incumbent is actually running for reelection (in an analysis not shown here). Summer presidential approval accounts for 23 percent of the variation in election outcomes in the following year. Removing two influential outliers — the 1964 and 1992 elections — from the analysis does not change the finding. The results suggest that the incumbent party becomes the bare favorite to win when its president’s net approval rating is slightly positive in the summer of the year before an election, at +4. Currently, HuffPost Pollster estimates President Obama’s net rating to be just the opposite, at -4, making the Republicans narrowly favored to win the 2016 election by a predicted margin of 51 percent to 49 percent.
