# What is percent error/percent deviation?

Aug 15, 2017

relative error between experimental and true results

#### Explanation:

Percent error and percent deviation are the same thing. They both measure the relative error when you compare the results you got (the experimental/measured results) and compare them to the true or accepted results.

They determine the accuracy of your results. The smaller your percent error, the better your results are. Usually ± 5% is acceptable in class. If it is higher, you might need to go back through your experiment to see what systematic or random errors were present.

Depending on your teacher/professor, the equation for percent error could be one of two equations. I will list both. Just use the one that your professor wants you to use. Some may want you to use the absolute value to express % error as a positive number only.

% error = (x_(measured)-x_(true))/x_(true)*100%

% error = abs((x_(measured)-x_(true))/x_(true))*100%