For frequency distribution, the mean deviation
is given by:
M.D = ∑ ∣X−X ∣
n
the mean deviation is When calculated about the
median, the formula become :
M.D (about median) =∑ f |X−Median|
Σ
The mean deviation about the mode is:
M.D (about mode)=∑f|X−Mode|
∑f
For a population data the mean deviation about the
population mean μ is
M. D =∑ f |X− μ|
∑f
For a population data the mean deviation about the
population mean μ is
M. D = ∑ f |X –μ |
∑f