I'm designing a UI for a long and complex questionnaire, to do with legal services.
My client feels that almost every section should start with a "Does this apply? Y/N" question, forcing the user to make a choice, so the client can be sure that the user has consciously looked at the question. The alternative is to allow the user to leave fields blank - this may make for a cleaner UI but it may be unclear whether the user has deliberately left the question blank or missed it by accident.
The questionnaire will be used face-to-face with people in potentially difficult situations, and because of the unpredictable nature of the meetings it's hard to predict the order in which questions will be answered and there won't be any 'required' fields because some things won't apply.
Can anyone point to any resources or examples about data collection design that may help, or point to any experiences you've had with something similar?
Many thanks, Tom