Page 30 - DECO504_STATISTICAL_METHODS_IN_ECONOMICS_ENGLISH

Statistical Methods in Economics

Notes So the discrete data of marks obtained by 25 students is:

Marks Obtained Number of Students
2 7
4 5
6 7
8 3
10 3
Formation of Continuous Frequency Distribution
In continuous frequency distribution data are divided into class intervals instead of individual values
(as is done in case of discrete frequency distribution) class intervals can be formulated like marks
from 0 to 10, 10 – 20 and so on. Here the magnitude of class interval is 10 marks. (20 – 10 = 10). But it
can be lower, for example, 0 – 5, 5 – 10 and so on or higher, like 0 – 20, 20 – 40 and so on.
Suppose, the marks obtained of 100 students is to be given in continuous series, it can be done as
below:
Marks Obtained Number of Students

0–10 14
10–20 26
20–30 30
30–40 20
40–50 10
100

This means 14 students obtained marks between ‘0’ (zero) to 10. The marks may lie in any fraction 1/
3 3
4, 3 , 9 , 9.99 or 10, and likewise. These are called exclusive class intervals.
4 4
Sometimes, the data is given as below:
Marks Obtained Number of Students

10–19 4
20–29 6
30–39 10
40–49 10
30
This is called inclusive class arrangement. In this case, a question arises as to in which class the
student getting 9.5 or 29.5 must be placed ? In such a case to ensure continuity following adjustments
must be made:

Marks obtained Number of Students
9.5–19.5 4
19.5–29.5 6
29.5–39.5 10
39.5–49.5 10
30

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