Median

#Math
Central tendency measure that minimizes the sum of the L1 norm between it and all the other points.

$$

\text{Med}(X)=
\begin{cases}
X\left[ \frac{n+1}{2} \right], & n\text{ is odd} \\\text{mean}\left( X\left[ \frac{n}{2} \right],X\left[ \frac{n+1}{2} \right] \right), & n\text{ is even}
\end{cases}
$$

• The middle value of an odd-length list or the average of the two middle values of an even-length list
• $\displaystyle X$ is an ordered list