Cognitive scientists use the term “availability bias” to refer to the human tendency to generalize based on nearby information. In this case, we could speak of first-order and second-order availability biases. A national survey of journalists found that about twice as many are Democrats as Republicans. Presumably their friends and acquaintances are also more likely to support Democrats, and a first-order availability bias would lead a journalist to overestimate Democrats’ support in the population — as in the notorious quote misattributed to movie critic Pauline Kael.
Political journalists are well aware of the latest polls and election forecasts and are unlikely to make such an elementary mistake. However, they can easily make the second-order error of assuming that the correlations they see of income and voting are representative of the population
. The aforementioned survey found that 90% of journalists are college graduates and their incomes are mostly above the national average — so it is natural for them to think that they and their friends represent Democrats as a whole. It is easy for elite journalists to falsely project an incorrect correlation of income and Demoratic voting on the general population.
Again, we are using Michael Barone as an example precisely because he is so well informed but is still vulnerable to the cognitive traps that affect us all.
Another form of availability bias is that the centers of national journalistic activity include the relatively rich states of New York, California, Maryland, and Virginia. Once again, journalists — and, for that matter, academics — avoid the first-order availability bias: they are not surprised that the country as a whole votes different from the residents of big cities. But they sometimes make the second-order error of too quickly generalizing from the correlations in their states. Richer counties tend to support the Democrats within the media centers of Maryland, Virginia, New York, and California, but not, in general, elsewhere. And richer voters support the Republicans just about everywhere, but this pattern is much weaker — and thus easier to miss — within these richer states.
Andrew Gelman, Red State, Blue State, Rich State, Poor State (2008)
I suspect there may sometimes be a racial bias as well — I’ll be interested to see if Gelman discusses this. I think for a lot of political journalists, lower-income black and Hispanic voters code as non-white rather than lower income, and therefore their voting preferences are discounted.