Global Polling Problems

Many posts have discussed the mounting problems facing public opinion research. The polls greatly underestimating the showing of Likud in Isreal and the Tories in Britain.  At FiveThirtyEight, Nate Silver sees a pervasive problem:

Perhaps it’s just been a run of bad luck. But there are lots of reasons to worry about the state of the polling industry. Voters are becoming harder to contact, especially on landline telephones. Online polls have become commonplace, but some eschew probability sampling, historically the bedrock of polling methodology. And in the U.S., some pollsters have been caught withholding results when they differ from other surveys, “herding” toward a false consensus about a race instead of behaving independently. There may be more difficult times ahead for the polling industry.