## What is a good standard deviation?

To get an approximate answer, calculate your coefficient of variation (CV = standard deviation/mean). In general, CV >= 1 indicates a relatively high variation, while CV 1 can be considered low. … A good SD depends on whether you expect your distribution to be centered or distributed around the mean.

## What is a high standard deviation?

The standard deviation (or σ) is a measure of how spread out the data is about the mean. A low standard deviation means the data clusters around the mean, while a high standard deviation means the data is more spread out.

## What does a standard deviation of 2.5 mean?

A normal distribution with mean 0 and standard deviation 1 is called a standard normal distribution. … For example, a Z of 2.5 is a value that is 2.5 standard deviations below the mean. The area under Z is 0.0062.

## How do you interpret the standard deviation?

Specifically, it is a measure of the average distance between the data values in a 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 negative?

This means that distributions with a coefficient of variation greater than 1 are considered highly dispersive and distributions with a coefficient of variation less than 1 are considered low dispersive. Remember that standard deviations are neither good nor bad. … There is no good or maximum standard deviation.

## What does the 20 standard deviation mean?

For all test results, the standard deviation is the square root of 75.76 or 8.7. …If you have 100 items in your data set and the standard deviation is 20, there is a relatively large deviation of the values from the mean. If you have 1,000 items in your data set, a standard deviation of 20 is much less significant. 24

## What are 2 standard deviations from the mean?

For a roughly normal data set, values within one standard deviation of the mean are about 68% of the total, while values within two standard deviations are about 95%, and within three types are about 95%. 99.7%.