Any of you know a good solution for this problem with cross-validation? @lakens @randal_olson @gwern http://stats.stackexchange.com/questions/213837/k-fold-cross-validation-nominal-predictor-level-appears-in-the-test-data-but-no … #rstats
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(Binary dummies mean that the lm always 'sees' each level but may always be 0s in the training subset)
Not sure how you would do this. The level is still there in the training data, just no case has it.