In mathematics, an<unk> , or central tendency of a data set refers to a measure of the "middle" or "expected" value of the data set. There are many different descriptive statistics that can be chosen as a measurement of the central tendency of the data items. The most common method is the arithmetic mean, but there are many other types of<unk> s.
Colloquially, people often use the term<unk>  to refer to an intuitive central tendency without having a specific measurement of central tendency in mind, or use terms such as "the<unk>  person". However, the phrase "there's no such thing as an<unk>  citizen" emphasizes that the<unk>  is a number, not a person or some other object.  The<unk>  is calculated by combining the measurements related to a group of people or objects, to compute a number as being the<unk>  of the group.
Average
Median
Arithmetic mean
Mean lifetime
Incidence 
Trends 
Dose Profile
Prevalence