After the 2012 election, political scientists John Sides and Lynn Vavreck wrote a book called “The Gamble” that looked at the cause of President Obama’s victory over Mitt Romney. They sifted through the quantitative voting and polling data and concluded that the supposedly game-changing events — like Romney’s “47 percent” comment, or Obama’s poor debate performance in Denver — had no effect on the outcome.

What mattered, they found, was the direction of the economy. The decline in unemployment, and the growth in GDP, was just enough for Obama to make a credible case for his reelection. Everything else was just noise.

Likewise, there are two statistical measurements that, more than anything else, will determine whether the White House changes parties in 2016: Obama’s job approval and the direction of the country, measured by whether voters think we’re on the right track or the wrong track.

In terms of job approval, Obama has been under 50 percent for most of his presidency. The most recent Real Clear Politics monthly polling average says just 45 percent of Americans approve of the job Obama has been doing, while 52 percent disapprove. If the president remains net negative, voters should expect to hear a lot from Republicans on how the Democratic nominee is really running for Obama’s third term.