Mean Plus 1 Standard Deviation. In statistics the 68 95 99 7 rule also known as the empirical rule is a shorthand used to remember the percentage of values that lie within a band around the mean in a normal distribution with a width of two four and six standard deviations respectively. And dachshunds are a bit short right.
More precisely 68 27 95 45 and 99 73 of the values lie within one two and three standard deviations of the mean respectively. Because standard deviation is a measure of variability about the mean this is shown as the mean plus or minus one or two standard deviations. If the mean of a dataset is 25 and its standard deviation is 1 6 then 68 of the values in the dataset will lie between mean 1sd 25 1 6 23 4 and mean 1sd 25 1 6 26 6 99 of the values will lie between mean 3sd 25 4 8 20 2 and mean 3sd 25 4 8 29 8.
Rottweilers are tall dogs.
If the observations follow a normal distribution a range covered by one standard deviation above the mean and one standard deviation below it. Standard deviation may be abbreviated sd and is most commonly. If the observations follow a normal distribution a range covered by one standard deviation above the mean and one standard deviation below it. The reason why the standard deviation is such a useful measure of the scatter of the observations is this.
