I just read this “post”:http://www.huffingtonpost.com/michael-p-mcdonald/the-age-gap-and-what-it-p_b_807746.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+pollster%2Fallcontent+%28Pollster.com+All+Content%29 by Michael McDonald about turnout and the 2010 House elections. His point: an age gap has developed in recent elections, with young people voting increasingly Democratic relative to the elderly. That makes the consequences of low turnout in midterm elections by young people more significant. He estimates that Democrats would have received about one percent more of the vote in 2010 if young people had turned out at the same rate as they did in 2008.
This estimate was particularly interesting to me because it’s similar in magnitude to the effect of campaign mobilization that John and I found in a recent “paper”:http://springerlink.metapress.com/content/0190-9320/?k=mcghee (gated) we wrote together. Basically, we found that big shifts in campaign activity can change the partisan complexion of the electorate by a couple percentage points, independent of the broader political climate. Nor are we the first to find that mobilization matters. Others, including “Daron Shaw”:http://www.jstor.org/stable/2585400 (gated) and “Thomas Holbrook and Scott McClurg”:http://www.jstor.org/stable/3647691 (gated), have found important results for mobilization, too.
It may seem surprising that the effect of turnout is not larger. There’s a sense that the kind of turnover we witnessed in 2010 should require a _completely_ different electorate if turnout is to be a factor. But when so many outcomes are decided right at the 50% mark, a percentage point or two can make a big difference. In fact, the closeness of the races in 2010 helps explain why we found such a big effect of roll call votes like the health care bill: it wasn’t that the effect of those roll calls was all that large in absolute terms, but it didn’t need to be to produce a huge change in seats. After all, the Republicans took back the House with a national shift in the two-party vote of around seven percent or so.