Download Standard Deviation – Measure of Spread in Distributions

Standard Deviation – Measure of Spread in Distributions
Mean
x
Variance
x
i
2 
 (x
n
Standard Deviation
i
 x)
2
n

 (x
i
 x) 2
n
1. Consider the data set {40, 52, 54, 74, 80}
a) Determine the mean.
b) Determine the standard deviation.
c) The variance is the square of the standard deviation.
What is the variance for the above data set?
2. The standard deviation is the square root of the variance. If
the variance is 12.5, what is the standard deviation?
Small standard deviation means data is close to mean.
Large standard deviation means data is widely scattered.
(See example #2 on page 165)