Questionnaires often seem a logical and easy option as a way of collecting information from people. They are actually rather difficult to design and because of the frequency of their use in all contexts in the modern world, the response rate is nearly always going to be a problem (low) unless you have ways of making people complete them and hand them in on the spot (and this of course limits your sample, how long the questionnaire can be and the kinds of questions asked).
As with interviews, you can decide to use closed or open questions, and can also offer respondents multiple-choice questions from which to choose the statement which most nearly describes their response to a statement or item. Their layout is an art form in itself because in poorly laid out questionnaires respondents tend, for example, to repeat their ticking of boxes in the same pattern.
If given a choice of response on a scale 1-5, they will usually opt for the middle point, and often tend to miss out subsections to questions. You need to take expert advice in setting up a questionnaire, ensure that all the information about the respondents that you need is included and filled in, and ensure that you actually get them returned.
Expecting people to pay to return postal questionnaires is sheer folly, and drawing up a really lengthy questionnaire will also inhibit response rates. You will need to ensure that questions are clear, and that you have reliable ways of collecting and managing the data. Setting up a questionnaire that can be read by an optical mark reader is an excellent idea if you wish to collect large numbers of responses and analyze them statistically rather than reading each questionnaire and entering data manually.
You would find it useful to consult the range of full and excellent research books available. These will deal in much greater depth with the reasons for, processes of holding, and processes of analyzing data from the variety of research methods available to you.
Developing and Using a Questionnaire
Identify your research questions
Identify your sample
Draw up a list of appropriate questions and try them out with a colleague
Ensure questions are well laid out and it is clear how to 'score them' (tick, circle, delete)
Ensure questions are not leading and confusing
Code up the questionnaire so you can analyze it afterwards
Gain permission to use questionnaires from your sample
Ensure they put their names or numbers on so you can identify them but keep real names confidential
Hand them out/post them with reply paid envelopes
Ensure you collect in as many as possible
Follow up if you get a small return
Analyze statistically if possible and / or thematically
What kind of research methods are you going to use? Are they mostly:
Quantitative, or qualitative, or a mixture of both?
What do you think your methods will enable you to discover?
What might they prevent you from discovering?
What kinds of research methods would be best suited to the kind of research you are undertaking and the research questions you are pursuing?
What sort of problems do you envisage in setting up these methods?
What are their benefits?
What will you need to do to ensure they gather useful data?