When people speak of statistics, they usually mean one or more of the following:
1. Numerical data such as the unemployment rate, the number of persons who die annually from bee stings, or the racial makeup of the population of New York City in 2006 as compared to 1906.
2. Numbers used to describe samples (subsets) of data, such as the mean (average), as opposed to numbers used to describe populations (entire sets of data); for instance, if we work for an advertising firm interested in the average age of people who subscribe to Sports Illustrated, we can draw a sample of subscribers and calculate the mean of that sample (a statistic), which is an estimate of the mean of the entire population of subscribers.
3. Particular procedures used to analyze data, and the results of those procedures, such as the t statistic or the chi-square statistic.
4. A field of study that develops and uses mathematical procedures to describe data and make decisions regarding it.
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