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16 Cards in this Set

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  • Back
  • 3rd side (hint)
Population
The whole - complete group
Sample
a sub set of the population
statistics from samples are often used to make inferences about a population
Parameter
Numerical data that describes a Population
Statistic
numerical measure that describes a Sample
measures of central tendency
mean
median
mode
average
center location
most frequent
Levels of measurement
1 Nominal
2 Ordinal
3 Interval
4 ratio
the listing is from least to most specific measurment
mean
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
median
center
mode
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.
Measures of Dispersion
Range
Variance
Standard deviation
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
outlier
data value that varies significantly from the other values - they effect the mean
Variance
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
Variance formula for a sample
Sum of X - X-bar squared
divided by n-1
this formula is weighted
Variance formula for a Population
sum of X - U squared divided by n
symol for mean is a greek letter that looks like a U
Standard deviation
Square root of the variance for both populations and Samples the calculation gives us the value = to 1 standard deviation
deviation from the mean in standard units