Page 199 - DSOC404_METHODOLOGY_OF_SOCIAL_RESEARCH_ENGLISH

Unit-27: Measures of Central Tendency: Mean, Median, Mode

7 20 (7 – 6) = +1 (20 × 1) = 20 note
8 11 (8 – 6) = +2 (11 × 2) = 22
9 6 (9 – 6) = +3 (6 × 3) = 18
10 5 (10 – 6) = +4 (5 × 4) = 20
11 5 (11 – 6) = +5 (5 × 5) = 25
12 1 (12 – 6) = +6 (1 × 6) = 6
13 1 (13 – 6) = +7 (1 × 7) = 7
Sfd = (– 2362 + 118)
total Sf = 735
= – 2244
formula for calculation of arithmetic average using short-cut method
S fd
M = A +
f S
Here assumed mean A = 6
∑ fd = – 2244
∑f = 735 (Number of families)
− 2244
therefore, M = 6 +
735
= 6 – 3.05
= 2.94 or 3 children.
therefore, the arithmetic average of number of children born in each family = 3 children

Task How do we calculate arithmetic average in a discrete series? Describe.

27.5 calculation of Mean in continuous series

if the frequency of class intervals is given then we can calculate the mean using two techniques—
one is direct method and the other is short-cut method. Here both the techniques are described
separately.
(a) Direct-method—the mean for continuous series is calculated using direct method in the same
way.

Did You Know? Direct method is used for calculation of mean in continuous series. in this
only one stage is extra that in this method we find the mean of class intervals
and in this way we convert the continuous series into discrete series.

in this way we can present the direct method in this way-

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