It compares how large the error is to the magnitude of the measurement. Relative error is based on the absolute error value. If you are using a ruler that reports length to the nearest millimeter, you might say the absolute error of any measurement taken with that ruler is to the nearest 1 mm or (if you feel confident you can see between one mark and the next) to the nearest 0.5 mm. Some people consider absolute error to be a measure of how accurate your measuring instrument is. If you measure the length of a sample three times and get 1.1 cm, 1.5 cm, and 1.3 cm, then the absolute error is +/- 0.2 cm or you would say the length of the sample is 1.3 cm (the average) +/- 0.2 cm. You could report the error with a sign, so the absolute error in this example could be -0.2 m/s 2. Absolute error is simply the difference between the measured value and either the true value or the average value of the data.Ībsolute error = measured value – true valueįor example, if you measure gravity to be 9.6 m/s 2 and the true value is 9.8 m/s 2, then the absolute error of the measurement is 0.2 m/s 2. This measure of accuracy is reported using the units of measurement. One method of measuring error is by calculating absolute error, which is also called absolute uncertainty. So, you need to know the different types and sources of error and how to calculate them. If there is a large margin of error, you’ll be asked to go over your procedure and identify any mistakes you may have made or places where error might have been introduced. The amount of error that is acceptable depends on the experiment, but a margin of error of 10% is generally considered acceptable.

The difference between your results and the expected or theoretical results is called error.

This helps you evaluate your results and compare them against other people’s values. Science labs usually ask you to compare your results against theoretical or known values. All science experiments contain error, so it’s important to know the types of error and how to calculate it.

How to find percent error