Standard Deviation
The standard deviation of an observation variable is the square root of its variance.
Problem
Find the sample standard deviation of the eruption duration in the data set faithful.
Solution
We apply the sd function to compute the sample standard deviation of eruptions.
> duration = faithful$eruptions # the eruption durations
> sd(duration) # apply the sd function
[1] 1.1414
> sd(duration) # apply the sd function
[1] 1.1414
Answer
The sample standard deviation of the eruption duration is 1.1414.
Exercise
Find the sample standard deviation of the eruption waiting periods in faithful.
