Mean absolute deviation for grouped data
Let $(x_i,f_i), i=1,2, \cdots , n$ be given frequency distribution. Then the sample mean is given by
$$ \begin{aligned} \overline{x}&=\frac{1}{N}\sum_{i=1}^n f_ix_i. \end{aligned} $$
Formula
The mean absolute deviation about mean for grouped data is given by
$MAD =\frac{1}{N}\sum_{i=1}^{n}f_i|x_i -\overline{x}|$
where,
$N =\sum_{i=1}^n f_i$total number of observations$\overline{x}$sample mean
