A bit of advice (which you probably won't need, either, but still...) Let someone try out your questionnaire, someone who doesn't know yet what you are trying to achieve. That way you find out where something isn't as clear as it seems to you (or anybody else in the know). It's just that I've seen too many questionnaires (and info leaflets etc), written by "experts", that were so badly designed as to be quite meaningless in the end...