What is 2 standard deviations from the mean?
68% of the data is within 1 standard deviation (σ) of the mean (μ), 95% of the data is within 2 standard deviations (σ) of the mean (μ), and 99.7% of the data is within 3 standard deviations (σ) of the mean (μ)..
Is a standard deviation of 1 GOOD?
For an approximate answer, please estimate your coefficient of variation (CV=standard deviation / mean). As a rule of thumb, a CV >= 1 indicates a relatively high variation, while a CV < 1 can be considered low. ... Remember, standard deviations aren't "good" or "bad". They are indicators of how spread out your data is.
What does it mean if the standard deviation is 1?
A normal distribution with a mean of 0 and a standard deviation of 1 is called a standard normal distribution. Areas of the normal distribution are often represented by tables of the standard normal distribution. … For example, a Z of -2.5 represents a value 2.5 standard deviations below the mean.
What is the standard deviation if the mean is 0?
This means that for every i, the term (xi – x )2 = 0. This means that every data value is equal to the mean. This result along with the one above allows us to say that the sample standard deviation of a data set is zero if and only if all of its values are identical.
Is the mean of a normal distribution always 0?
The normal distribution is a symmetrical, bell-shaped distribution in which the mean, median and mode are all equal. It is a central component of inferential statistics. The standard normal distribution is a normal distribution represented in z scores. It always has a mean of zero and a standard deviation of one.
Why is the standard deviation 0?
The more spread out a data distribution is, the greater its standard deviation. Interestingly, standard deviation cannot be negative. A standard deviation close to 0 indicates that the data points tend to be close to the mean (shown by the dotted line).