Mean absolute error

In statistics, the mean absolute error (MAE) is a quantity used to measure how close forecasts or predictions are to the eventual outcomes. The mean absolute error is given by

As the name suggests, the mean absolute error is an average of the absolute errors ${\displaystyle |e_{i}|=|f_{i}-y_{i}|}$, where ${\displaystyle f_{i}}$ is the prediction and ${\displaystyle y_{i}}$ the true value. Note that alternative formulations may include relative frequencies as weight factors.

The mean absolute error used the same scale as the data being measured. This is known as a scale-dependent accuracy measure and therefore cannot be used to make comparisons between series using different scales.

...
Wikipedia