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# Measures of centre

### The mean

• The mean is the average of the data points. Can be calculated by: $\bar{x} = \frac{\mbox{sum of all observations}}{\mbox{ total number of observations} }$
• The mean can also be denoted $$\bar{y}$$.
• Used for quantitative data.
• For example a nurse measured a patient’s temperature (in degrees Celcius) $$4$$ times $$( 37.2$$, $$37.5$$, $$37.1$$, $$37.3)$$, the mean temperature will be:
• \begin{eqnarray*}
\bar{x} &=& \frac{ \mbox{sum of all observations}}{\mbox{total number of observations} }\\
&=&\frac{37.2+ 37.5+ 37.1+ 37.3}{4} \\
&=& 37.275 \\
&\approx& 37.3^\circ\mbox{C}
\end{eqnarray*}