Accuracy percentage-wise of a regression model [duplicate]

I would like to check in percentage the accuracy of my regression model. I know that normally accuracy is used as a metric for classification. I have evaluated my model based on r-squared and also plotted the y_pred versus y_test.

However, I find it easier to understand the prediction performance in terms of accuracy. Therefore, I would like to do something like this (based on the sklearn, metrics.mean_absolute_percentage_error) :

accuracy = 100 - np.mean(mean_absolute_percentage_error(y_test,y_pred))
print('Accuracy:', round(accuracy, 2), '%.')

Does it make sense, would the result reflect the performance of the regression model based on a percentage of accuracy?

• Are you sure of how to interpret such a score? For instance, do you know that a percentage of $50\%$ is like an $\text{F}$-grade in school that indicates a poor model? Do you know if $90\%$ is like an $\text{A}$-grade in school that indicates an excellent model? // I disagree with this being a duplicate of the MAPE question, though that information is pertinent.
– Dave
Nov 3 '21 at 11:01
• @Dave, I understand the analogy, however, I find it easier to understand in percentage terms rather than an r-squared of 0.4 (for instance). It does not mean that the model is performing better or worse, it could be still pretty bad, just a different way to communicate the same result. Nov 3 '21 at 11:08
• Then why not take $R^2=0.4$ as $40\%$ performance?
– Dave
Nov 3 '21 at 11:17

$$R^2$$ and MAPE do not communicate the same result. $$R^2$$ elicits the conditional expectation, and MAPE elicits the (-1)-median. Those are two different functionals of the underlying distribution.