Empirical rule calculator - a statistics tool also known as 68-95-99.7 rule, or three sigma (3σ) rule calculator to determine the percentage of values around the mean for the standard deviation width of 1σ, 2σ & 3σ to analyse the normally distributed (bell shaped curve) statistical data. The term 68-95-99.7 in normal distribution represents 68.27%, 95.45% and 99.73% of data around the mean for the width of 1σ, 2σ & 3σ respectively.
The Empirical Rule is applicable to the bell shaped curve or normally distributed data. The range of the data fall from the mean can vary from 1 to 3 standard deviations or fall within plus or minus 3 standard deviations. The Empirical Rule for normal distribution or bell shaped curve defines that 68% of the observations roughly expected to fall within 1σ of the mean, 95% of the observations expected to fall within 1σ of the mean and 99.73% of the data values can be expected fall within 1σ interval from the mean. To mention it more accurately 68.27%, 95.45% and 99.73% of data fall around the mean for the width of 1σ, 2σ & 3σ respectively.
In statistical data analysis, when working along with standard deviation calculation, there may be many occassions that the user may need to find the percentage of data fall around the mean. Therefore calculating the percentage of data around the mean is very much important in such calculations very often. When it comes to online, this Empirical Rule (68-95-99.7) or 3σ calculator easily determine the data percentage around the mean with respect to the width of 1σ, 2σ & 3σ in a normally distributed data set.