another percentage problem?

Question

is there a difference between percentage error and percentage difference? if so, what is it??

Answer 1

These terms are really confusing. Percentage Error is really the same thing as Percentage Increase (or Decrease), and is usually used to figure out how much a measured value is from an expected value (think scientific measurements). So if you wanted to know the Percentage Error of the value 3 from the expected value of 5...

(3 - 5)/5 = -.40 = -40%

This tells us that our value of 3 was 40% below the expected value of 5


Percentage difference is used when we don't have an expected value to reference. It is defined scientifically as:

|value1 - value2| / ((value1 + value2)/2)

Or difference divided by the mean. So for 3 and 5...

|3 - 5| / ((3+5)/2) = .50 = 50%

Percentage Difference is a measure of how similar two values are. A value of 0% indicates that there is no difference, and the larger the percent the greater the difference between the values.

Answer 2

I believe they are usually pretty close but may be different; for example, if you are aiming for a 10 but get a 9, it may be said that the error is 10%. However, if you only consider the two values and want to know the percent of difference you take the average of the percent difference from 9 to 10 and the percent difference from 10 to 9.