Difference between revisions of "Random sampling"
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An example is all eligible voters being equally likely to be included in a poll. This method does not ensure accuracy, but increases its likelihood. | An example is all eligible voters being equally likely to be included in a poll. This method does not ensure accuracy, but increases its likelihood. | ||
| + | ==Theory== | ||
In statistical studies, '''random sampling''' refers to the extraction of values (''sampling'') of a designated input [[probability distribution]] for ensuing statistical calculations, such that the relative [[probability]] of extraction is that indicated by the input [[probability density function]] in the case of a continuous distribution or the [[probability mass function]] in the case of a discrete distribution. | In statistical studies, '''random sampling''' refers to the extraction of values (''sampling'') of a designated input [[probability distribution]] for ensuing statistical calculations, such that the relative [[probability]] of extraction is that indicated by the input [[probability density function]] in the case of a continuous distribution or the [[probability mass function]] in the case of a discrete distribution. | ||
| + | ==Further reading== | ||
| + | * Graham Kalton. ''Introduction to Survey Sampling'' (Quantitative Applications in the Social Sciences) (1983) [http://www.amazon.com/Introduction-Sampling-Quantitative-Applications-Sciences/dp/0803921268/ref=sr_1_2?ie=UTF8&s=books&qid=1235831356&sr=1-2 excerpt and text search[ | ||
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| + | [Category:Statistics]] | ||
Revision as of 14:31, February 28, 2009
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.
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.)
An example is all eligible voters being equally likely to be included in a poll. This method does not ensure accuracy, but increases its likelihood.
Theory
In statistical studies, random sampling refers to the extraction of values (sampling) of a designated input probability distribution for ensuing statistical calculations, such that the relative probability of extraction is that indicated by the input probability density function in the case of a continuous distribution or the probability mass function in the case of a discrete distribution.
Further reading
- Graham Kalton. Introduction to Survey Sampling (Quantitative Applications in the Social Sciences) (1983) [http://www.amazon.com/Introduction-Sampling-Quantitative-Applications-Sciences/dp/0803921268/ref=sr_1_2?ie=UTF8&s=books&qid=1235831356&sr=1-2 excerpt and text search[
[Category:Statistics]]