The coefficient of variation (CV) is an alternate way to measure variation. The CV expresses the standard deviation as a percent of the mean. Because it has no unit of measure, you can use the coefficient of variation to compare the variability of data with different units of measure. Note: Either the sample standard deviation, ss, or the population standard deviation, σσ, may be used for calculating the CV. Use the appropriate value of the standard deviation depending on whether the data pertain to a population or a sample.
CV=standard deviationMean×100%
| Table 6. Line voltage at a computer. | ||||||||
| Protection | Line voltage (volts) | |||||||
| No Surge Protector | 73 | 140 | 78 | 142 | 80 | 140 | 90 | 133 |
| With Surge Protector | 100 | 120 | 108 | 114 | 105 | 117 | 103 | 114 |
17. Find the coefficient of variation for the voltages with no surge protector (Round your answer to 3 decimal places).
18. Find the coefficient of variation for the voltages with a surge protector (Round your answer to 3 decimal places).
19. What do you conclude from the results in questions 17 and 18?.