Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

Let's say I have two numbers that I know to have been normalized- 39, 12. How do I calculate the percentage difference between them? Is it the same as if they hadn't been normalized? ie: (12/39) * 100

share|improve this question

1 Answer 1

up vote 0 down vote accepted

Shouldn't the percentage difference be [(12-39)/39]*100 or [(39-12)/12]*100? Note that you get different answers, not just the negative-when the two numbers are unequal the percentage difference depends upon which you regard as the base.

Whether normalization changes the percentage depends upon what you mean by normalization. Sometimes it is multiplication by a constant to bring the range to something you like. This will not impact the percentage difference-try multiplying 39 and 12 by a and note that it divides out of the expression. Sometimes it involves adding or subtracting a constant-that will make a difference. Compare [(39-12)/39]*100 to [(30-3)/30]*100. The answer is different. Sometimes it is a more complicated expression, which will almost always change the percentages.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.