Measure of Variation

Measure of Variation
Used to asses the variation of data around the mean or median or mode

• Range
• the numerical difference between the minimum and maximum values in a data set
• Variance
• calculate in squared unites of the original data
• population
• sample
• Standard deviation
• measure of the spread of data around a mean
• Standard error
• describes dispersion of sample mans around their population mean
• Coefficient of variation
• used to compare amount of variation among samples with data that differs in magnitude

Variance 

• 2 step process
• Find SS
• Divide SS by n-1=df
• use n-1=df 
• Conservative estimate of the population variance