Measure
Excel Function
Mean
=AVERAGE
Median
=MEDIAN
3
Right-Skewed
Left-Skewed
Symmetric

Mode
=MODE.SNGL
3.2 Measures of Variability
The
Range
The Benefit of the range is - easy to calculate, easy to understand
Formula for the Range:
Highest Value – Lowest Value
The
Variance
The variance is a more useful measure of variability because it uses all data values.
Formula for the Sample Variance
Formula for the Population Variance
Where:
x
i
=
minus the sample mean is the difference between each data value and the sample mean
s
2
=
the sample variance
σ
2
= the population variance
n = the sample size
N = the population size
x
= the sample mean
µ= the population mean
The
Standard Deviation
Unlike the variance, the standard deviation’s units are not squared.
Formula for the Sample Standard Deviation
Formula for the Population Standard Deviation
Where:
s = standard dev.
σ = standard dev.
What Excel Functions can be used to calculate the Variance and Standard Deviation/
4

Measure
Excel Function
Sample Variance
=VAR.S
Sample Standard Deviation
=STDEV.S

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- Fall '12
- Donnelly
- Standard Deviation