... questionnaires are undertaken by trained researchers who guide respondents through the questions. This eliminates errors and misunderstandings. Postal questionnaires are mailed to respondents with a Stamped Addressed Envelope. This type of questionnaire is cheap and is sent to a large number of people over a large geographical area. Another type of questionnaire can be done over a phone. This is widely used by market researchers. Questionnaires should be piloted previous to the answering in the real trials. Checks for reliability and validity are important, and once you have a good questionnaire, very often good results are produced. The results can be used to compare subjective opinions over different situations and development phases. The types of questions used in questionnaires are Closed-ended and Open-ended questions. Closed-ended questions give an element of choice. They have a finite set of answers from which the respondent chooses. One of the choices may be 'Other'. It is ...

See this essay or coursework document in full right now