Mean
The mean of an observation variable is a numerical measure of the central location of the data values. It is the sum of its data values divided by data count.
Hence, for a data sample of size n, its sample mean is defined as follows:
Similarly, for a data population of size N, the population mean is:
Problem
Find the mean eruption duration in the data set faithful.
Solution
We apply the mean function to compute the mean value of eruptions.
> duration = faithful$eruptions # the eruption durations
> mean(duration) # apply the mean function
[1] 3.4878
> mean(duration) # apply the mean function
[1] 3.4878
Answer
The mean eruption duration is 3.4878 minutes.
Exercise
Find the mean eruption waiting periods in faithful.
