That’s what Dan Schnur, the director of the Jesse M. Unruh Institute of Politics at the University of Southern California, told Adam Nagourney in a front page article, “In California, Asking Voters to Raise Taxes,” in today’s New York Times.

According to Schnur, “The November 2012 ballot is going to be the political equivalent of bumper car. What we have seen historically is that voters who are overwhelmed or overloaded with things tend to vote ‘no’ on everything.”

While it sounds convincing, Mr. Schnur’s statement is not really backed up by the data.

In California, between 1911 and 2010, voters considered 1180 statewide initiatives, popular referendums, and legislative referendums, passing 666 of them, for a passage rate of 56%.  When it comes to statewide initiatives, popular referendums, and legislative referendums on the ballot in general elections, Californians have approved 491 of the 893 measures.

Here’s a graph of the number of general election statewide ballot measures by year in California, and the accompanying passage rates, over time:

It’s pretty hard to discern a clear relationship over the years that suggests that an increased number of measures on the statewide ballot leads to a decreased percentage of measures adopted by the voters.

Here’s another look at the same data, using a scatterplot:

Again, there’s not a very clear pattern over the last century when looking at the number of statewide ballot measures in a general election and the overall passage rate of those measures. As the linear regression equation indicates, the relationship is quite weak. (And no, that’s not a data entry error: there really were 47 measures on California’s statewide ballot in 1914).

So, what are we to make of Mr. Schnur’s comment, in light of the data?

More measures on the ballot does not lead necessarily to lower overall support for ballot propositions. California voters don’t get “overloaded.”

California voters are not stupid, and are certainly not “dumber than chimps” as Skip Lupia rightly notes. They are able to pick and choose down the ballot, even very long ones, making binary choices that best match their own preferences. It is essential, of course, that voters have informational cues, or heuristics (such as campaign spending on a ballot measure that indicates support or opposition by vested interests) which can help voters with their civic duty when serving as lawmakers for a day.

So bring on the ballot measures in 2012, even those raising taxes on the wealthy to pay for educational and energy programs. Californians are up for the challenge.