Mean deviation is the average of the deviations of

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Unformatted text preview: e items in a distribution from an appropriate average. Thus, we calculate mean deviation from mean, median or mode. Theoretically, mean deviation from median has an advantage because sum of deviations of items from median is the minimum when signs are ignored. However, in practice, mean deviation from mean is frequently used. That is why it is commonly called as mean deviation. Formula for calculating mean deviation Sikkim Manipal University = ΣD/N Page No. 192 Research Methodology Unit 11 Where ΣD = sum of the deviation of the items from mean, median or mode N = number of items D is mode less meaning values or deviation is taken without signs. Steps 1. Calculate mean, median or mode of the series 2. Find the deviation of items from the mean, median or mode 3. Sum the deviations and obtain ΣD 4. Take the average of the deviations ΣD/N, which is the mean deviation. The co- efficient of mean deviation is the relative measure of mean deviation. It is obtained by dividing the mean deviation by a particular measure of average used for measuring mean deviation. If mean deviation is obtained from median, the co-efficient of mean deviation is obtained by dividing mean deviation by median. The co-efficient of mean deviation = mean deviation / median If mean deviation is obtained from mean, the co-efficient of mean deviation is obtained by dividing mean deviation by mean. The co-efficient of mean deviation = mean deviation / mean If mean deviation is obtained from mode, the co-efficient of mean deviation is obtained by dividing mean deviation by mode. The co-efficient of mean deviation = mean deviation / mode Problems Calculate mean deviation for the following data from mean Daily wages : 15 18 20 25 30 35 40 42 45 Frequency : 2 3 5 10 12 10 5 2 1 Sikkim Manipal University Page No. 193 Research Methodology Daily wages 15 Unit 11 Frequency f. x D =x-20 Fd 2 30 5 10 18 3 54 2 6 20 5 100 0 0 25 10 250 5 50 30 12 360 10 120 35 10 350 15 150 40 5 200 20 100 42 2 84 22 44 45 1 45 25 25 50 1473 Mean = 20 = ΣfD/N = 505...
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