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Measures of Dispersion
Why is standard deviation also known as the root mean square deviation?
Standard deviation is also known as the root mean square deviation because it is the square root of the means of the square deviation from the arithmetic mean. In the calculation of standard deviation, first the arithmetic average is calculated, and the variations of various items from arithmetic averages are squared. The squared deviations are totalled and the sum is divided by the number of items. The square root of the resulting figure is the standard deviation of the series. The S.D. is denoted by the Greek letter. σ (Sigma) Symbalically
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In the previous question, calculate the relative measures of variation and indicate the value, which in your opinion is more reliable.
If in the previous question, each worker is given a hike of 10% in wages, how are the mean and standard deviation values affected?
The sum of 10 values is 100 and the sum of their squares is 1090. Find the coefficient of variation.
Calculate the mean deviation about mean and standard deviation for the following distribution:
|
Classes |
Frequencies |
|
20–40 |
3 |
|
40–80 |
6 |
|
80–100 |
20 |
|
100–120 |
12 |
|
120–140 |
9 |
|
50 |
A measure of dispersion is a good .supplement to the central value in understanding a frequency distribution. Comment
Define dispersion.
How many methods are there to calculate dipersion?
Define range.
Define quartile deviation.
How is coefficient of quartile deviation calculated?
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