The answer is Mean
More to the definition...
(X) The sum of set of scores divided by the number of scores summed.
- Arithmetic average
-Most common measurement of central tendency
-Influenced by extreme scores
-Data should have interval properties; can not be used with nominal or ordinal data
-Sample mean is the best estimator of population mean.
-Can be manipulated algebraically.
-Any change of a score in the distribution affects the mean