Math and Arithmetic

Statistics

Percentages, Fractions, and Decimal Values

# Can percent error be negative?

###### 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.

## Related Questions

###### Asked in Math and Arithmetic, Statistics, Algebra

### What does it mean if you get a negative number when you calculate for percent error?

Depending on whether you subtract actual value from expected
value or other way around, a positive or negative percent error,
will tell you on which side of the expected value that your
actual value is. For example, suppose your expected value is 24,
and your actual value is 24.3 then if you do the following
calculation to figure percent error:
[percent error] = (actual value - expected value)/(actual value)
- 1 --> then convert to percent.
So you have (24.3 - 24)/24 -1 = .0125 --> 1.25%, which tells
me the actual is higher than the expected. If instead, you
subtracted the actual from the expected, then you would get a
negative 1.25%, but your actual is still greater than the expected.
My preference is to subtract the expected from the actual. That way
a positive error tells you the actual is greater than expected, and
a negative percent error tells you that the actual is less than the
expected.

###### Asked in Math and Arithmetic, Chemistry

### What is the percent error formula for mass of pennies?

For any percent error formula:
100 x (Experimental Value - Theoretical Value) / Theoretical
Value
Take the absolute value of this (make it positive) , and give it
a percent sign.
Example: The listed mass was 1 gram, and you found it to be .9
grams
100(0.9-1)= -10
-10/1 =-10
-10 becomes 10
10% error
You will NEVER have a negative percent error, and its a good
idea to write "error" after the percent sign.

###### Asked in Math and Arithmetic, Statistics, Percentages, Fractions, and Decimal Values

### What is the formula for percent error?

The formula of percent error is
percent error= Your value/accepted value x 100
------------
The definition of error is: difference between the accepted true
value and the measured value of a quantity or parameter. But this
is the absolute error.
The relative (percent error) is:
(measured value - accepted true value) . 100/accepted true
value
This value is exprssed as a percentage - %.

###### Asked in Math and Arithmetic, Chemistry, Statistics, Percentages, Fractions, and Decimal Values

### What is the percent error formula?

Percent Error is the difference between the true value and the
estimate divided by the true value and the result is multiplied by
100 to make it a percentage. The percent error obviously can be
positive or negative; however, some prefer taking the absolute
value of the difference.
The formula is the absolute value of the experimental value
(minus) the theoretical value divided by theoretical value times
100.
% error = (|Your Result - Accepted Value| / Accepted Value) x
100