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3 statistic

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a cura della classe IE scientifico a.s. 2011-12 con la guida della prof.ssa M. Montanarelli

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3 statistic

1. 1. Statistics is the study of the collection, organization, analysis and interpretation ofdata. It deals all aspects of this, including the planning of data collection in terms of the design of surveys and experiments.
2. 2. Descriptive statistics summarize the population data by describing what was observed in the sample numerically or graphically. Numerical descriptors include mean and standard deviation forcontinuos data types (like heights or weights), while frequency andpercentage are more useful in terms of describing categorial data (like race).
3. 3. In statistics, meanhas two relatedmeanings: the arithmetic mean(and is distinguishedfrom the geometricmean or harmonicmean). the expected valueof a random variable ,which is also calledthe population mean.
4. 4. There are other statistical measures that should not be confused with averages – including ‘median’ and ‘mode’. Other simple statistical analyses use measures of spread, such as range,interquartile range, or standard deviation. For a real-valued random variable X, the mean is the expectation of X. Note that not every probability distribution has a defined mean (or variance).
5. 5. Standard deviation is a widely used measure ofvariability or diversity used in statistics and probability theory. It shows how much variation or “dispersion” exists from the average (mean, or expected value). A low standard deviation indicates that the data points tend to be very close to the mean, whereas high standard deviation indicates that the data points are spread out over a large range of values.
6. 6. ESEGUITO DAMANUEL DE CHIARAVALERIE DE CHIARAFRANCESCO FORTUNATOANTONIO VERNI