22 September 2004

Why to ignore the polls

Robert explains it all for you:

…If you decide to trust all polling agencies equally, the thing to do is
to average weighted by the inverse of the square of the reported
standard error. This means that estimates of Bush’s lead in September
would be roughly halved by the ARG result ! From 3 – 5 % to 2 – 3%. If
you have decided to ignore Gallup, CBS and Time, you have to decide
whether to ignore ARG too.

Why did I say embarassingly low ?

I think pollsters use small samples only partly to save money, and also
to give themselves an excuse if their numbers are off. With a huge
sample, a difference between the poll and the election would imply a
more worrisome problem, either a biased sample, a faulty likely voter
filter or a psychological difference between talking to a pollster and
actually voting. It is clear that some or all sampling techniques give
biased samples, because the spread of polls is to large to explain with
sampling error alone. Polling agencies certainly don’t want to spend
money to prove that they are one of the agencies with a defective
sampling technique.

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