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16 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Population
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The whole - complete group
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Sample
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a sub set of the population
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statistics from samples are often used to make inferences about a population
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Parameter
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Numerical data that describes a Population
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Statistic
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numerical measure that describes a Sample
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measures of central tendency
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mean
median mode |
average
center location most frequent |
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Levels of measurement
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1 Nominal
2 Ordinal 3 Interval 4 ratio |
the listing is from least to most specific measurment
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mean
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average
formula Sum of X divided by n |
symbols sample mean X bar - X with a line over it
population mean symbol that looks like U |
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median
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center
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mode
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most
unimodal one mode Bi modal 2 modes multi modal 3 or more modes |
often used instead of mean if the data is very skewed.
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Measures of Dispersion
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Range
Variance Standard deviation |
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Range
Interquartile Range |
maximum Value minus minimum value = range of data
Q3-Q1 gives the range of the middle |
If a value is added to each X in a distribution or sample this measure will not change
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outlier
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data value that varies significantly from the other values - they effect the mean
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Variance
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shows the amt of dispersion from the mean/ average of dispersion
for the sample or population |
Symbols
Sample S2 supra script Population greek symbol for alpha also with supra script 2 |
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Variance formula for a sample
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Sum of X - X-bar squared
divided by n-1 |
this formula is weighted
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Variance formula for a Population
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sum of X - U squared divided by n
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symol for mean is a greek letter that looks like a U
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Standard deviation
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Square root of the variance for both populations and Samples the calculation gives us the value = to 1 standard deviation
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deviation from the mean in standard units
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