Changes

'''Random sampling''' is a [[statistical]] technique which gives everyone in the target group the same opportunity to participate in a [[poll]]. Moree exactly, everyone has a known probability of selectionb. This ensures the '''validity''' of the poll, meaning that the results reflect the target population.

'''Random sampling''' is a [[statistical]] technique in which individuals are randomly selected from the target group (usually a sub-set of the population). More precisely, everyone has a known probability of selection. Generally the aim of this method is to remove bias in selection of samples, though it may not be suitable for all cases of statistical analysis, depending upon the circumstances.

The '''reliability''' of a poll is a different dimension and refers to the amount of random error still present. The larger the poll, the smaller the random error. (Increasing the size of a poll by X reduces the error by the square root of x. A poll with 4 times as many people  will have half the random error.)

The '''reliability''' of a poll is a different dimension and refers to the amount of random error still present. The larger the poll, the smaller the random error. (Increasing the size of a poll by X reduces the error by the square root of x. A poll with 4 times as many people  will have half the random error.)