title: sklearn metrics units of Measurement of accuracy, mean absolut error, mean squared error for regression problems?
body: <p>Which unit of measurement has the accuracy, mean absolut error and mean squared error of the sklearn metrics? and are they used for regression problems? 
  For example i have a regressor.score(X_test,y_test)) of about 0.99469. So the tested Model is 0.99469 in comparison to the real data? or do you say percent of 99%? 
  The same with the MAE and MSE. </p>
  
  <p>The other question is, i red about the confusion matrix for classification problems and the accuracy is the value calculated out of the confusion matrix. I use a multiple linear regression, so can i use these metrics for my regression? </p>