Knowledge Networks used traditional telephone and mail sampling methods to randomly recruit respondents.

MSN: Poll reveals baby boomers' retirement fears

The Census Bureau thinks the only way to improve the numbers is to make more use of statistical sampling methods.

ECONOMIST: Statistics

If it used these sampling methods, the Census Bureau says, there is a 90% chance that its estimate of America's population would be within 0.1% of the true number.

ECONOMIST: Statistics

Improper sampling could also impact the accuracy of common methods used to measure the performance of the predictive coding tool being used.

FORBES: Guest Post by Matthew Nelson

In India many more sampling points have been established, and in all countries better survey methods, relying on surveyors knocking on doors rather than asking questions at clinics, have gathered data from more representative samples.

ECONOMIST: AIDS