What is a good standard deviation?
What is a good standard deviation?
For an approximate answer, please estimate your coefficient of variation (CV = standard deviation / mean). In general, a CV >= 1 indicates relatively high variation, while a CV 1 can be considered low. … A good SD depends on whether you expect your distribution to be centered or spread around the mean.
What is a high standard deviation?
A standard deviation (or σ) is a measure of how spread out the data are from the mean. A low standard deviation means the data clusters around the mean, and a high standard deviation means the data is more spread out.
What does a standard deviation of 2.5 mean?
A normal distribution with a mean of 0 and a standard deviation of 1 is called the standard normal distribution. … For example, a Z of 2.5 represents a value that is 2.5 standard deviations below the mean. The area under Z is 0.0062.
How do you interpret a standard deviation?
In particular, it is a measure of the average distance between the data values in the set and the mean. A low standard deviation indicates that the data points tend to be very close to the mean. A high standard deviation indicates that the data points are spread over a wide range of values.
Is a high standard deviation bad?
This means that distributions with a coefficient of variation greater than 1 are considered high variance, while distributions with a CV less than 1 are considered low variance. Remember that standard deviations are neither good nor bad. … There is no good or maximum standard deviation.
What does a standard deviation of 20 mean?
For all test results, the standard deviation is the square root of 75.76, or 8.7. … If you have 100 items in a data set and the standard deviation is 20, there is a relatively large deviation of the values from the mean. If you have 1000 items in a dataset, a standard deviation of 20 is much less meaningful. 24
What is 2 standard deviations from the mean?
For a roughly normal data set, values within one standard deviation of the mean account for about 68% of the whole, while within two standard deviations account for about 95%, and within three types for about 99.7%.
