Math and Arithmetic
Statistics
Percentages, Fractions, and Decimal Values

Can percent error be negative?

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Wiki User
January 08, 2011 9:53PM

Sometimes you will take the absolute value of the percent error because your estimated number could be less than the theoretical, meaning the calculation is negative. But an absolute value is always positive. A percent error can be left as a negative though, and this would be perfectly acceptable (or even preferred) depending on what you're doing.

Answer:

In the sciences, a negative percent error indicates a low result. If you have a 0% error, then your observed (lab) result was exactly the same as the theoretical result. A 5% error could mean that your observed result was a little high. A negative percent error is possible; if your observed results were lower than the expected, then you would have a negative percent error. A -5% error could mean that your results were a little low.

Having a negative percent error isn't worse than positive percent error -- it could mean the same thing. If you were to have a choice in having a 20% error and a -5% error, the negative percent error is more accurate.