LESSON 4 MEASURES OF DISPERSION LESSON 4 MEASURES OF DISPERSION Why dispersion? Measures of central tendency, Mean, Median, Mode, etc., indicate the central position of a series. They indicate the general magnitude of the data but fail to reveal all the peculiarities and characteristics of theseries. In other words, they fail to reveal the degree of the spread out or the extent of the variability inindividual items of the distribution. This can be explained by certain other measures, known as ‘Measures ofDispersion’ or Variation. We can understand variation with the help of the following example : ---------------------------------------------- Series 1 Series 11 Series III --------------------------------------------- 10 2 10 10 8 ...
LEARNING OUTCOMES At the end of this module, you will be able to: produce and interpret frequency distribution tables; produce and interpret graphs *********************************************************** FREQUENCY DISTRIBUTION: Data can be presented in various forms depending on the type of data collected. A frequency distribution is a table showing how often each value (or set of values) of the variable in question occurs in a data set. A frequency table is used to summarize categorical or numerical data. Frequencies are also presented as relative frequencies, that is, the percentage of the total number in the sample. EXAMPLE : Frequency distribution of peptic ulcer according to site of ulcer Site of ulcer Frequency Percent Gastric ulcer 24 30.0 Duodenal ulcer 50 62.5 Gastric and duodenal ulcer 6 7.5 TOTAL 80 100 GRAPHICAL METHODS: Frequency distributions and are usually illustrated graphically by plotting various type...
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