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Unformatted text preview: e value above which there can be no item to that class. Of the
class 60-79, 60 is the lower limit and 79 is the upper limit, i.e. in
the case there can be no value which is less than 60 or more than
79. The way in which class limits are stated depends upon the
nature of the data. In statistical calculations, lower class limit is
denoted by L and upper class limit by U.
b) Class Interval:
The class interval may be defined as the size of
grouping of data. For example, 50-75, 75-100, 100-125…are
intervals. Each grouping begins with the lower limit of a
interval and ends at the lower limit of the next succeeding
class c) Width or size of the class interval:
The difference between the lower and upper class limits is
called Width or size of class interval and is denoted by ‘ C’ .
The difference between largest and smallest value of the
observation is called The Range and is denoted by ‘ R’ ie
R = Largest value – Smallest value
R = L-S
e) Mid-value or mid-point:
The central point of a class interval is called the mid value
or mid-point. It is found out by adding the upper and lower limits
of a class and dividing the sum by 2.
For example, if the class interval is 20-30 then the mid-value is
20 + 30
Number of observations falling within a particular class
interval is called frequency of that class.
Let us consider the frequency distribution of weights if
persons working in a company.
(i.e.) Midvalue = Weight
In the above example, the class frequency are
25,53,77,95,80,60,30. The total frequency is equal to 420. The
total frequency indicate the total number of observations
considered in a frequency distribution.
g) Number of class intervals:
The number of class interval in a frequency is matter of
importance. The number of class interval should not be too many.
For an ideal frequency distribution, the number of class intervals
can vary from 5 to 15. To decide the numb...
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This note was uploaded on 01/18/2014 for the course BUS 100 taught by Professor Moshiri during the Winter '08 term at UC Riverside.
- Winter '08