(a) Symmetrical Distribution,
(b) Moderately Skewed or Asymmetrical Distribution,
(c) Extremely Skewed or J-Shaped Distribution,
(d) U-Shaped Distribution, and
(e) Multi-Modal Distribution.
(a) Symmetrical Distribution: A frequency distribution is said to be symmetrical if the frequencies equidistant from the maximum are equal.
| Class interval |
0-9
|
10-19
|
20-29
|
30-39
|
40-49
|
50-59
|
60-69
|
| Frequency |
2
|
5
|
9
|
12
|
9
|
5
|
2
|
(b) Moderately Skewed or Asymmetrical Distribution: A
frequency distribution is said to be skewed when it departs from
symmetry, i.e., when the frequencies tend to pile up in one end or the
other end of a distribution.
Asymmetrical distributions are of two types, i.e.:
(i) Positively skewed, and
(ii) Negatively skewed.
(i) Positively Skewed:
| Class interval |
0-9
|
10-19
|
20-29
|
30-39
|
40-49
|
50-59
|
60-69
|
| Frequency |
2
|
5
|
12
|
9
|
7
|
4
|
1
|
(ii) Negatively Skewed:
| Class interval |
0-9
|
10-19
|
20-29
|
30-39
|
40-49
|
50-59
|
60-69
|
| Frequency |
1
|
4
|
7
|
9
|
12
|
5
|
2
|
(c) Extremely Skewed or J-Shaped Distribution:
| Income |
0-1999
|
2000-3999
|
4000-5999
|
6000-7999
|
8000-9999
|
10000-11999
|
12000-13999
|
| No. of persons |
4000
|
3000
|
2500
|
1500
|
500
|
350
|
150
|
(d) U-Shaped Distribution: In such a distribution, the maximum frequencies occur at both ends and a minimum in the centre.
| Class interval |
1-5
|
6-10
|
11-15
|
16-20
|
21-25
|
26-30
|
| Frequency |
45
|
30
|
18
|
12
|
24
|
40
|
(e) Multi-Modal Distribution:
1. Frequency distributions with more than one maximum are called ‘multi-modal distribution’.
2. A distribution with two maxima is called a ‘bimodal distribution’.
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