If I have a regression or classification problem
y ~ x1 + x2 + ... + xn
I might call the
xi the regressors or the predictors. But what do you call
The terms regressand and predictand are clunky, don't seem particularly standard, and have the disadvantage that they're very similar to the words for the right-hand-side variables (I'm going to be using these terms in type declarations and documentation for a program, so minimizing the potential for confusion is a priority).
Also, using regressor and regressand is inappropriate when you have a classification problem, rather than a regression.
Is there a commonly used term?