This concern, however, is being allayed with the advent of techniques such as Dr Song's mobile-sampling method.

ECONOMIST: The biology of business

It is a victory for congressional Republicans, who brought the lawsuit arguing that the sampling method was unconstitutional.

ECONOMIST: Sampling is wrong: official

Because the 1990 Census undercounted millions of Americans, mostly minorities, the Clinton administration proposed the sampling method as a way of ensuring a more accurate count in 2000.

ECONOMIST: Sampling is wrong: official

Have each group write up its sampling, method and questions, and then exchange its poll with another group.

CNN: Student News Learning Activity: Polling

In the name of correcting the undercount of people in our cities, Democrats want to implement so-called sampling, a computerized polling method that adjusts population counts.

FORBES: Fact and Comment

However, the researchers said that despite a lower number of invasive tests, the heavier reliance of this method on chorionic villus sampling earlier in pregnancy could actually mean an increase in the number of healthy babies lost if the miscarriage rate using this method was closer to 2%.

BBC: Down's test miscarriage warning

The difference this new method can make was dramatically illustrated in January when Gallup made its switch from quota sampling.

ECONOMIST: Why the polls got it wrong last time