• Questionnaires are easy to analyze.
• Easy to complete
• Questionnaires are familiar to most people
• Questionnaires reduce bias
• Questionnaires are less intrusive than telephone or face-to-face surveys.

Disadvantages Of Written Questionnaires

• One major disadvantage of written questionnaires is the possibility of low response rates.
• Another disadvantage of questionnaires is the inability to probe responses.

Questionnaire Design - General Considerations

• Most problems with questionnaire analysis can be traced back to the design phase of the project. Well-defined goals are the best way to assure a good questionnaire design.
  
• Be sure to commit the study goals to writing. Avoid the temptation to ask questions because it would be "interesting to know".
  
• As a general rule, with only a few exceptions, long questionnaires get less response than short questionnaires. Keep your questionnaire short. In fact, the shorter the better.
  
• Give your questionnaire a title that is short and meaningful to the respondent. A questionnaire with a title is generally perceived to be more credible than one without.
  
• Include clear and concise instructions on how to complete the questionnaire.
  
• Use simple and direct language. The questions must be clearly understood by the respondent.
  
• Leave adequate space for respondents to make comments. Leaving space for comments will provide valuable information not captured by the response categories. Leaving white space also makes the questionnaire look easier and this increases response.
  
• Place the most important items in the first half of the questionnaire.
  
• If a questionnaire is more than a few pages and is held together by a staple, print only one side of the page.
  
• The final test of a questionnaire is to try it on representatives of the target audience. If there are problems with the questionnaire, they almost always show up here. If possible, be present while a respondent is completing the questionnaire and tell her that it is okay to ask you for clarification of any item.

Qualities of a Good Question

• Evokes the truth. When a respondent is concerned about the consequences of answering a question in a particular manner, there is a good possibility that the answer will not be truthful. Anonymous questionnaires that contain no identifying information are more likely to produce honest responses than those identifying the respondent.
  
• Asks for an answer on only one dimension. The purpose of a survey is to find out information. A question that asks for a response on more than one dimension will not provide the information you are seeking. For example, a researcher investigating a new food snack asks "Do you like the texture and flavor of the snack?" If a respondent answers "no", then the researcher will not know if the respondent dislikes the texture or the flavor, or both.

• Can accommodate all possible answers. Multiple choice items are the most popular type of survey questions because they are generally the easiest for a respondent to answer and the easiest to analyze. Asking a question that does not accommodate all possible responses can confuse and frustrate the respondent. For example, consider the question:

  What brand of computer do you own? __
  A. IBM PC
  B. Apple

  Clearly, there are many problems with this question. What if the respondent doesn't own a microcomputer? What if he owns a different brand of computer? What if he owns both an IBM PC and an Apple? There are two ways to correct this kind of problem.

  The first way is to make each response a separate dichotomous item on the questionnaire. For example:

  Do you own an IBM PC? (circle: Yes or No)

  Do you own an Apple computer? (circle: Yes or No)

  Another way to correct the problem is to add the necessary response categories and allow multiple responses. This is the preferable method because it provides more information than the previous method.

  What brand of computer do you own?
  (Check all that apply)
  __ Do not own a computer
  __ IBM PC
  __ Apple
  __ Other

• Has mutually exclusive options. A good question leaves no ambiguity in the mind of the respondent. There should be only one correct or appropriate choice for the respondent to make. An obvious example is:

  Where did you grow up? __
  A. country
  B. farm
  C. city

  A person who grew up on a farm in the country would not know whether to select choice A or B. This question would not provide meaningful information.

• Produces variability of responses. When a question produces no variability in responses, we are left with considerable uncertainty about why we asked the question and what we learned from the information. If a question does not produce variability in responses, it will not be possible to perform any statistical analyses on the item. For example:

  What do you think about this report? __
  A. It's the worst report I've read
  B. It's somewhere between the worst and best
  C. It's the best report I've read

  Since almost all responses would be choice B, very little information is learned. Design your questions so they are sensitive to differences between respondents. As another example:

  Are you against drug abuse? (circle: Yes or No)

  Again, there would be very little variability in responses and we'd be left wondering why we asked the question in the first place.

• Does not presuppose a certain state of affairs. Among the most subtle mistakes in questionnaire design are questions that make an unwarranted assumption. An example of this type of mistake is:

  Are you satisfied with your current auto insurance? (Yes or No)

  This question will present a problem for someone who does not currently have auto insurance. Write your questions so they apply to everyone. This often means simply adding an additional response category.

  Are you satisfied with your current auto insurance?
  ___ Yes
  ___ No
  ___ Don't have auto insurance

  One of the most common mistaken assumptions is that the respondent knows the correct answer to the question. Industry surveys often contain very specific questions that the respondent may not know the answer to. For example:

  What percent of your budget do you spend on computers? ____

  Very few people would know the answer to this question without looking it up, and very few respondents will take the time and effort to look it up.

  It is important to look at each question and decide if all respondents will be able to answer it. Be careful not to assume anything. For example, the following question assumes the respondent knows what Proposition 13 is about.

  Are you in favor of Proposition 13 ?
  ___ Yes
  ___ No
  ___ Undecided

  If there is any possibility that the respondent may not know the answer to your question, include a "don't know" response category.

• Does not imply a desired answer. The wording of a question is extremely important. We are striving for objectivity in our surveys and, therefore, must be careful not to lead the respondent into giving the answer we would like to receive. Leading questions are usually easily spotted because they use negative phraseology. As examples:

  Wouldn't you like to receive our free brochure?

  Don't you think the Congress is spending too much money?
  

• Does not use unfamiliar words or abbreviations. Remember who your audience is and write your questionnaire for them. Do not use uncommon words or compound sentences. Write short sentences.

  What was your AGI last year? ______

• Is not dependent on responses to previous questions. Branching in written questionnaires should be avoided. While branching can be used as an effective probing technique in telephone and face-to-face interviews, it should not be used in written questionnaires because it sometimes confuses respondents. An example of branching is:

  1. Do you currently have a life insurance policy ? (Yes or No) If
  no, go to question 3

  2. How much is your annual life insurance premium ? _________

  These questions could easily be rewritten as one question that applies to everyone:

  1. How much did you spend last year for life insurance ? ______

• Does not ask the respondent to order or rank a series of more than five items. Questions asking respondents to rank items by importance should be avoided.

Question Wording

• The wording of a question is extremely important. Researchers strive for objectivity in surveys and, therefore, must be careful not to lead the respondent into giving a desired answer. Unfortunately, the effects of question wording are one of the least understood areas of questionnaire research.
  
• Many investigators have confirmed that slight changes in the way questions are worded can have a significant impact on how people respond. Several authors have reported that minor changes in question wording can produce more than a 25 percent difference in people's opinions.
  
• Several investigators have looked at the effects of modifying adjectives and adverbs. Words like usually, often, sometimes, occasionally, seldom, and rarely are "commonly" used in questionnaires, although it is clear that they do not mean the same thing to all people. Some adjectives have high variability and others have low variability. The following adjectives have highly variable meanings and should be avoided in surveys: most, numerous, a substantial majority, a minority of, a large proportion of, a significant number of, many, a considerable number of, and several. Other adjectives produce less variability and generally have more shared meaning. These are: lots, almost all, virtually all, nearly all, a majority of, a consensus of, a small number of, not very many of, almost none, hardly any, a couple, and a few.

adapted from http://www.statpac.com/surveys/