Great analysis of pollsters and the media

[central scrutinizer]

http://election.princeton.edu/2008/10/17/the-economics-of-reporting-polls/#more-1917

The economics of reporting polls

The only thing happening in the national race is a slight, slow widening of Obama’s lead. Some of you want to know about individual polls, such as a recent Gallup national poll showing Obama ahead by only +2% (standard likely-voter model) or +6% (high-turnout model). I confess that I simply ignore individual polls, so it didn’t occur to me to care about this particular data point. Obama is still crushing McCain, period.

But there is a lesson to be learned here: It is not in the interest of individual pollsters or media organizations for you to have the most accurate possible picture of the horserace. Here is why.

Uncertainties such as the margin of error can be reduced by taking more samples. An individual pollster can halve the margin of error by surveying 4 times as many people. It’s a square-root relationship: N samples lead to a sqrt(N)-fold reduction in uncertainty. The same is true for combining polls, with the added advantage of reducing the effects of methodological variation. Thus the value of poll-aggregation sites like this one. Meta-Analysis worked extremely well in 2004 and 2006, and is likely to do so again this year.

snip
With news budgets on the decline, it’s costly to report real news. Why pay for investigative reporting when you can buy a poll and report the horserace? Within the area of poll reporting, market forces discourage high accuracy. For example, commissioning a survey of 4 times as many people would reduce uncertainty by a factor of two. But why pay 4 times as much for data that generate a lower likelihood of an apparent - and reportable - swing?

[nichomachus]

1. Not to mention that the media have an interest in a tight race

Who would have watched the debate if the polls were saying it was Obama 80 to McStain 15 with 5 percent undecided?