What you can — and can’t — expect to learn from the North Carolina special election

On Wednesday morning, one of the major parties is going to be irrationally exuberant and the other will be despondent once the results are in from the special election in North Carolina’s 9th Congressional District. But trying to read the tea leaves is almost always a useless exercise. Historical data shows that individual special elections don’t have much predictive power. We can get a decent read of public opinion by aggregating the results of many special elections. But we don’t need to go through that math when numerous polls are already telling us that the GOP is in bad shape. CONT.

David Byler, Washington Post