Definition
Measure of centre
A summary value used to describe the middle or typical part of a data set.
What it means
A data set may contain many values, so a measure of centre lets one value stand in for where the data are centred or what is typical. There is no single best choice for every data set: mean uses every numerical value, median uses the ordered middle, and mode uses what occurs most often.
Remember it
One value stands near the centre of the data crowd.
Example
For 2, 3, 3, and 8, the mean is 4, the median is 3, and the mode is 3. All three are measures of centre, but the high value 8 pulls the mean above the other two.
Watch for
A measure of centre is not always halfway between the smallest and largest values, and it is not always the mean.
Common mix-up
“Average” often means the arithmetic mean, but measures of centre are a family that also includes median and mode.
Exact meaning
A measure of centre is a summary value chosen to represent the central or typical location of a data set. Mean, median, and mode are common measures of centre, and they need not give the same result.