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16 Cards in this Set
 Front
 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
Q3Q1 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  Xbar squared
divided by n1 
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
