Page 224 - DSOC404_METHODOLOGY_OF_SOCIAL_RESEARCH_ENGLISH

Methodology of Social Research

notes Q − Q
Coefficient of Quartile Deviation = 3 1
Q + Q 1
3
for the above example,
30 15 15
−
Coefficient of Quartile Deviation = =
30 15 45
+
1
=
3
28.4 Mean Deviation

Mean deviation is the arithmetic mean of difference of each element of the series with the mean of
the series. According to Ghosh and Chowdhury, if the sum of deviation of each member of the series
from its mean is divided by the number of members, then the result is known as mean deviation. in
other words, first calculate the individual deviation of each element from the mean of series, then
sum up all the deviation, divide the sum by the number of elements, then the result is known as the
mean deviation. their main properties are:
1. it is calculated using mathematical techniques and involves each entity of the series.
2. Variation is calculated from the mean i.e. it can be arithmetic mean or median or mode. When
the variation is calculated using arithmetic mean, then it is known as mean deviation from
mean. When the variation is calculated using median, then it is known as mean seviation
from median, while when the variation is calculated using mode, then it is known as mean
deviation from mode.

self assessment
fill in the blanks:
1. Mean deviation is the ___________ of the difference of each element of series from the
mean.
2. if the sum of differences of deviations of individual elements from mean is divided by the
number of elements, then we obtain __________________.
3. the ____________ is calculated from mean, be it arithmetic mean, median or mode.

28.5 calculation of Mean Deviation

Calculation of mean deviation is done in the following ways:
a. If it required to find the mean of a simple series, then–

S d
d = =
δ
n
Where the different symbols used in the above equation are defined as
d = Mean deviation
∑d = sum of deviations of individual elements of series
from the mean (can be arithmetic mean/median/
mode)
n = Number of elements.

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