Definition
Centre
A centre is a middle point or typical middle location found by the rule for the object or data.
What it means
Centre does not just mean “looks roughly in the middle.” Use the rule for the thing. For a circle, the centre is the same distance from every point on the edge. For data, a measure of centre describes where the values are typically located.
Remember it
Ask, “Middle by which rule?”
Example
Draw any diameter of a circle. Its midpoint is the circle’s centre. If the diameter is 10 cm, every point on the circumference is 5 cm from that centre.
Watch for
A midpoint is halfway between two specified points. A centre may be found by another rule, so the words are not interchangeable in every situation.
Common mix-up
For data, centre is not automatically the mean; the median or another measure may describe the distribution more usefully.
Exact meaning
A centre is a point or location identified as central by a stated mathematical rule. A circle’s centre is equally distant from every point on its circumference; a data distribution’s centre is a typical middle location described by a measure such as the median or mean.