I am using the answers from a questionnaire for a classification problem. I discovered that a question can have nested sub-questions.. Let's say that I want to predict the age of a student based on some question..
i.e. the first question is
1) Did you pass your last exam? [x] yes  no  I haven't done it
and a person answers yes. In this case there is a subquestion
1_yes) What was the score? [x] A  B
How should I convert the answers into features to train my model?
Option 1) Treat them separately and transform them with one-hot-encoding I will have then the feature vector
pass_exam_yes - pass_exam_no - pass_exam_not_done - score_empty - score_A - score_B 1 - 0 - 0 - 0 - 1 - 0
Option 2) Merge the 2 answers and encoding the concatenation
pass_exam_yes_A - pass_exam_yes_score_B - pass_exam_no - pass_exam_not_done 1 - 0 - 0 - 0
I hope my question was clear enough