Mail Interview:The mail interview places a great deal of importance on the construction of the questionnaire because there is no interviewer in mail surveys to ask questions and record answers. It cannot be used to conduct an unstructured study. Personal and telephone interviews are more flexible in the sense that they can be stopped or altered at any point whereas the researcher has no control on the interview once the questionnaires is mailed. The mailing questionnaires is accompanied with a covering letter instructing the respondent how to complete the questionnaires and return the questionnaire to the researcher. The respondent s complete the questionnaire at the their own leisure and mail the replies to the researcher. This kind of interview requires that the questionnaire has to be even more carefully complied structured and pre tested than the personal interview questionnaires.