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| | Statistics Glossary - random variables and probability distributions (Site not responding. Last check: ) |
 | | The (population) variance of a random variable is a non-negative number which gives an idea of how widely spread the values of the random variable are likely to be; the larger the variance, the more scattered the observations on average. |
 | | Examples of discrete random variables include the number of children in a family, the Friday night attendance at a cinema, the number of patients in a doctor's surgery, the number of defective light bulbs in a box of ten. |
 | | Typically, a Geometric random variable is the number of trials required to obtain the first failure, for example, the number of tosses of a coin untill the first 'tail' is obtained, or a process where components from a production line are tested, in turn, until the first defective item is found. |
| www.stats.gla.ac.uk /steps/glossary/probability_distributions.html (2101 words) |
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