## What is 3 standard deviations below the mean?

The rule of thumb is that 99.7% of the observed data is within 3 standard deviations of the mean based on the normal distribution. Under this rule, 68% of the data is within one standard deviation, 95% is within two standard deviations, and 99.7% is within three standard deviations of the mean.

## What does it mean when the standard deviation is 3?

A standard deviation of 3 inches means that most men (about 68% in a normal distribution) are either 3 inches above or 3 inches below the mean (67-73), one standard deviation. … Three standard deviations include all numbers for 99.7% of the surveyed sample.

## What do 2 standard deviations below mean?

For some tests, the percentile ranks are close, but not exactly where you’d expect. A value that is two standard deviations above the mean is at or near the 98th percentile (PR = 98). A value that is two standard deviations below the mean is at or near the 2nd percentile (PR = 2).

## What is the standard deviation of the mean?

The Z-score, or standard value, is the number of standard deviations a given data point is above or below the mean. A score of 1 indicates that the data is one standard deviation from the mean, while a z-score of 1 places the data one standard deviation below the mean. … 8th

## Can we have more than 3 standard deviations?

The distribution share within 3 standard deviations of the mean can reach 88.9%. It can take more than 18 standard deviations to get to 99.7%. On the other hand, you can get more than 99.7% with much less than one standard deviation.