In Australia a decade ago the political professionals were caught quite unprepared for the Pauline Hanson phenomenon. With hindsight the major parties realised that the issues Ms Hanson tapped in to were issues that many people did not like admitting to openly, hence the problem of identifying those views in a poll.

If we look at this week’s New Hampshire primary, the pollsters got the Democratic contest very wrong with their predictions of an easy win for Obama over Hillary Clinton. We very polite journalists covering the phenomenon have tended to look towards the performance of candidate Clinton in the closing days of the New Hampshire campaign as an explanation. There has been a marked reluctance to suggest that it was not wanting to vote for a black man that led to pollsters getting one message and the ballot box another.

The closest I have come to seeing racism being described as the major factor was in the New York Times where Andrew Kohut, president of the Pew Research Centre, wrote that poorer, less well-educated white people refuse surveys more often than affluent, better-educated whites. According to Mr Kohut, polls generally adjust their samples for this tendency. “But here’s the problem: these whites who do not respond to surveys tend to have more unfavorable views of blacks than respondents who do the interviews.”

He continued:

I’ve experienced this myself. In 1989, as a Gallup pollster, I overestimated the support for David Dinkins in his first race for New York City mayor against Rudolph Giuliani; Mr. Dinkins was elected, but with a two percentage point margin of victory, not the 15 I had predicted. I concluded, eventually, that I got it wrong not so much because respondents were lying to our interviewers but because poorer, less well-educated voters were less likely to agree to answer our questions. That was a decisive factor in my miscall.

Certainly, we live in a different world today. The Pew Research Center has conducted analyses of elections between candidates of different races in 2006 and found that polls now do a much better job estimating the support for black candidates than they did in the past. However, the difficulties in interviewing the poor and the less well-educated persist.

Why didn’t this problem come up in Iowa? My guess is that Mr. Obama may have posed less of a threat to white voters in Iowa because he wasn’t yet the front-runner. Caucuses are also plainly different from primaries.

As to the difference between Iowa and New Hampshire it may be, regrettably, that there is a simpler explanation. In New Hampshire there was a secret ballot. In Iowa people had to put their hands up at a public meeting.

The next few ballots will tell the story.