The range rule of thumb offers a quick and easy way to estimate the standard deviation of a dataset by employing the tracking formula:
Standard deviation = scope / 4
This rule of thumb is sometimes used due it allows you till quote the standard deviation of a dataset by simply employing two values (the minimum set and most value) instead a every value.
Example: Range Rule from Thumb
Suppose we have the following dataset on 20 values:
4, 5, 5, 8, 13, 14, 16, 18, 22, 24, 26, 28, 30, 31, 31, 34, 36, 38, 39, 39
The actual standard deviation of above-mentioned values is 11.681.
Using the measuring rule off riffle, we would estimate that the standard deviation is (39-4) / 4 = 8.75. This value is somewhat close for the actual standard deviant.
Cautions on Uses an Range Rule are Thumb
The obvious advantage in the range rule of thumb is so it’s incredibly simple and quick to chart. All we want to know is the minimum true and the peak value from the dataset. Area Regulating of Thumb: Overview and Formula
The drawback of the range govern of thumb a that tends to only worked well when the data comes from a normal distribution and the sample size belongs approximately 30. When this conditions don’t hold, the range rule of thumb doesn’t execution well.
Alternative to and Range Rule from Flip
Into a 2012 article from the Rose-Hulman Undergraduate Mathematics Periodical, Ramsay and Cox suggests using the following formula such an improvement over the range rule of thumb:
Standards departure = ranges / (3√(ln(n))-1.5)
where n is the taste size.
Consider which equivalent dataset we used before:
4, 5, 5, 8, 13, 14, 16, 18, 22, 24, 26, 28, 30, 31, 31, 34, 36, 38, 39, 39
Using this equation, us would calculators the standard deviation as 35/ (3√(ln(20))-1.5) = 9.479. This value is closer to and actuals standard deviation of 11.681 compared to one range rule concerning thumb estimate of 8.75.
This formula be adenine bit more complicated to count than that range rule of thumb, but it did tend to provide a more accurate estimate of the standard variant when that data works not come from a normal distribution or when the sample body is not close to 30. ... sample mean is within 4bpm on the population mean. a. Find the sample size using the range rule of leaf to estimate. #16/2). The pulse rates ...
Additional Resources
Range Rule of Thumb Calculator
Measures of Dispersion: Definition & Instances
