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17 Cards in this Set
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Experiment

A systematic evaluation of the occurence of a phenomenon or of changes in a phenomenon, under wellspecified, controlled conditions.



Descriptive statistics

Summary numbers that describe the characteristics of a sample of items or events.



Statistics

The method of collecting, organizing, analyzing and reporting on numerical data derived from a sample.



Statistic

A number that summarizes some quality of a sample taken from a larger population.
The sample's mean is a statistic. 
"Something is missing from my enchilada"


Parameter

A number that represents the entire population.
The population's mean is a parameter. 
"The whole enchilada"


Central Limit Theorem

The sampling distribution of the mean approaches a <i>normal distribution</i> as the sample size increases



Sampling distribution

The hypothetical distribution of a statistic, such as a mean or a variance, derived from a sample.



Sample

A representative subset of the elements of a population.



Normal distribution

A collection of many sample points that forms a specific type of bellshaped, symmetrical curve.



Standard normal distribution

A normal distribution in which the mean is zero and the standard deviation is one.



(Arithmetic) mean

The sum of the values of all events in a sample or population divided by the number of events.
µ (MU) = Population's (Parameter's) mean X (Xbar) = Sample's mean 


Median

The value in the middle of the range of ordered values. If the range contains an even number of values it median is the average of the 2 middle values in the range.



Mode

With a set of values, the value that occurs with the greatest frequency. It is the single value most typical of all the values in the distribution.



Variance

The (population) variance of a random variable is a nonnegative 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.
A measure of dispersion. Variance is the average of the squared deviations from the mean  where "deviation" is the distance between the mean and each item in the population or sample. 


Standard deviation (SD)

A measure of dispersion. Standard deviation is the poitive square root of the variance.
Symbol = σ 


Confidence interval

An estimated range of values which is likely to include an unknown population parameter, the estimated range being calculated from a given set of sample data.



Variation

text

