We use the following basic statistical measures to gain deeper insights into how our process is performing.
Mean: The average of all values of a data set.
Median: The middle value of a data set when the values are arranged in either ascending or descending order
Mode: The mode common value of a data set.
Range: The span of numbers in the entire range of the set.
Standard Deviation – see article there.
Central Tendency – see article there.
Also related, Basic Probability