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Unformatted text preview: x D = x − Md 100
150
200
250
360
490
500
600
671
3321 269
219
169
119
9
121
131
231
302
1570 260
210
160
110
0
130
140
240
311
1561 M.D from mean = ∑D n
1570
=
= 174.44
9
M.D
Coefficient of M.D =
x
174.44
=
= 0.47
369
∑D
M.D from median =
n
1561
=
= 173.44
9
M.D
173.44
Coefficient of M.D.=
=
= 0.48
Median
360
7.5.4 Mean Deviation – Discrete series:
Steps: 1. Find out an average (mean, median or mode)
2. Find out the deviation of the variable values from the
average, ignoring signs and denote them by D
3. Multiply the deviation of each value by its respective
frequency and find out the total ∑ f D
151 ∑ f D by the total frequencies
∑f D
M.D. = 4. Divide
Symbolically, N N Example 7:
Compute Mean deviation from mean and median from the
following data:
Height 158 159 160 161 162 163 164 165 166
in cms
No. of
15
20
32
35
33
22
20
10
8
persons
Also compute coefficient of mean deviation.
Solution:
Height
No. of
X
persons
f
158
15
159
20
160
32
161
35
162
33
163
22
164
20
165
10
166
8
195
x = A+ d= x A
A =162 fd 4
3
2
1
0
1
2
3
4 D =
X mean  60
 60
 64
 35
0
22
40
30
32
 95 ∑ fd N
− 95
= 162 +
= 162 – 0.49 = 161.51
195
∑ f D = 338.59 = 1.74
M.D. =
N
195
152 3.51
2.51
1.51
0.51
0.49
1.49
2.49
3.49
4.49 fD 52.65
50.20
48.32
17.85
16.17
32.78
49.80
34.90
35.92
338.59 M.D
1.74
=
= 0.0108
161.51
X
No. of
D=
persons
c.f.
X − Median
f
15
15
3
20
35
2
32
67
1
35
102
0
33
135
1
22
157
2
20
177
3
10
187
4
8
195
5
195 Coefficient of M.D.=
Height
x
158
159
160
161
162
163
164
165
166 fD
45
40
32
0
33
44
60
40
40
334 th N +1 Median = Size of item
2
th 195 +1 = Size of item
2
= Size of 98 th item
= 161
∑ f D = 334 = 1.71
M.D =
195
N
1.71
M.D
=.0106
=
161
Median
7.5.5 Mean deviationContinuous series:
The method of calculating mean deviation in a continuous
series same as the discrete series.In continuous series we have to
find out the mid points of the various classes and take deviation of
these points from the average selected. Thus
∑f  D 
M.D =
N
Coefficient of M.D. = 153 Where D = m  average
M = Mid point
Example 8:
Find out the mean deviation from...
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 Winter '08
 Moshiri
 Business

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