Question 1

What is the formula for percent error?

Accepted Answer

Percent Error = |Experimental Value - Theoretical Value| / |Theoretical Value| x 100. The numerator is the absolute difference between the two values, and the denominator is the absolute value of the accepted theoretical value.

Question 2

Can percent error be negative?

Accepted Answer

The standard percent error formula uses absolute values, so the result is always non-negative. However, some fields use a signed version (without absolute value in the numerator) to indicate whether the experimental value is above (+) or below (-) the theoretical value.

Question 3

What is the difference between absolute error and relative error?

Accepted Answer

Absolute error is the raw difference: |Experimental - Theoretical|. Relative error divides the absolute error by the theoretical value, giving a dimensionless ratio. Percent error is the relative error expressed as a percentage (multiplied by 100).

Question 4

What is considered an acceptable percent error?

Accepted Answer

Acceptable percent error depends on the field. In introductory physics labs, 5-10% may be acceptable. In analytical chemistry, errors below 1% are often expected. In precision manufacturing, tolerances can be much tighter. Always check the requirements for your specific application.

Question 5

What if the theoretical value is zero?

Accepted Answer

When the theoretical value is zero, the percent error formula involves division by zero and is undefined. In such cases, use absolute error instead, or consider an alternative metric like mean absolute error for evaluating the measurement.

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