Unformatted text preview: alculated by the formula
Mode = L1 + (f1 – f0) / (2f1f0f2) X C L1 = Lower limit of the model class = 40 f1 = frequency of the model class = 27 f0 = frequency of the class preceding the model class = 15 f2 = frequency of the class succeeding the model class = 13 C = class interval 20 Mode = 40 + (27 – 15) / (2 X 27 –1513) X 20 = 40 + (12/ 5428) 20 = 40 + (12/ 26) 20 = 40 + (.4615) 20 = 40 + 9.23 = 49.23 Sikkim Manipal University = Page No. 185 Research Methodology Unit 11 Dispersion
Dispersion is the tendency of the individual values in a distribution to spread
away from the average. Many economic variables like income, wage etc.,
are widely varied from the mean. Dispersion is a statistical measure, which
understands the degree of variation of items from the average.
Objectives of Measuring Dispersion
Study of dispersion is needed to:
1. To test the reliability of the average
2. To control variability of the data
3. To enable comparison with two or more distribution with regard to their
variability
4. To facilitate the use of other statistical measures.
Measures of dispersion points out as to how far the average value is
representative of the individual items. If the dispersion value is small, the
average tends to closely represent the individual values and it is reliable.
When dispersion is large, the average is not a typical representative value.
Measures of dispersion are useful to control the cause of variation. In
industrial production, efficient operation requires control of quality variation.
Measures of variation enable comparison of two or more series with regard
to their variability. A high degree of variation would mean little consistency
and low degree of variation would mean high consistency.
Properties of a Good Measure of Dispersion
A good measure of dispersion should be simple to understand.
1. It should be easy to calculate
2. It should be rigidly defined
3. It should be based on all the values of a distribution
4. It should be amenable to further stati...
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 Spring '10
 smu
 Mean, Manipal University, Sikkim Manipal University

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