DQ for social research and statistics

If you decided to do a survey, why, or under what conditions, would you choose to do a self-administered questionnaire as opposed to a face-to-face interview with subjects, a telephone survey, or an email survey? What are the advantages and disadvantages of each type of survey? After you have answered this question, read the responses of your fellow students and discuss them. Ask questions about points you do not understand, explain why you think they are mistaken about some advantage or disadvantage, and add something that they did not mention. 

NO SPEACIAL ForMATT and NO SPECIFIC WORD COUNT...