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value of a discrete variable is distinct and separate. Examples of discrete
variables are gender of persons (male/female) occupation (salaried,
business, profession) car size (800cc, 1000cc, 1200cc)
In practice, all variables are treated as discrete units, the continuous
variables being stated in some discrete unit size according to the needs of a
particular situation. For example, length is described in discrete units of
millimetres or a tenth of an inch.
Class Intervals: Ordinarily, the number of class intervals may not be less
than 5 not more than 15, depending on the nature of the data and the
number of cases being studied. After noting the highest and lower values
and the feature of the data, the number of intervals can be easily
For many types of data, it is desirable to have class intervals of uniform size.
The intervals should neither be too small nor too large. Whenever possible,
the intervals should represent common and convenient numerical divisions
such as 5 or 10, rather than odd division such as 3 to 7. Class intervals must
be clearly designated in a frequency table in such a way as to obviate any
possibility of misinterpretation of confusion. For example, to present the age
group of a population, the use of intervals of 1-20, 20-50, and 50 and above
would be confusing. This may be presented as 1-20, 21-50, and above 50. Sikkim Manipal University Page No. 164 Research Methodology Unit 11 Every class interval has a mid point. For example, the midpoint of an interval
1-20 is 10.5 and the midpoint of class interval 1-25 would be 13. Once class
intervals are determined, it is routine work to count the number of cases that
fall in each interval.
One-Way Tables: One-way frequency tables present the distribution of
cases on only a single dimension or variable. For example, the distribution
of respondents of gender, by religion, socio economic status and the like are
shown in one way tables (Table 10.1) lustrates one-way tables. One way
tables are rarely used since the result of frequency...
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- Spring '10
- Mean, Manipal University, Sikkim Manipal University