Compare the strengths and weaknesses of mail questionnaire surveys and personal and telephone interviews. What are the situations most suitable for each of these methods?

What will be an ideal response?

Mail questionnaire surveys are low-cost, save time in labor, and can achieve a large sample size, but the process of collecting data takes longer and the quality of the data may be lower, depending on the ability and willingness of respondents to provide information. They are preferred when respondents are geographically scattered because they afford wider outreach to people who are difficult to locate and interview, and they also afford respondents the greatest privacy. However, they are automatically excluded from consideration when potential respondents cannot read and write, and tend to have high nonresponse rates. Another disadvantage of mail questionnaires is that they do not allow any interaction between researchers and respondents, but this also offers advantages in that it reduces the risk of bias and eliminates the need for fieldwork training. Mail questionnaires also allow the presentation of visual aids to help explain questions.

In regard to the instrument itself, the mail questionnaire survey must be relatively short, and it may not be appropriate for asking sensitive questions unless complete confidentiality can be assured. The mail survey is the most appropriate choice when the goal of research is to collect specialized information because it provides the opportunity for more considered answers and for respondents to check and secure information or consult with others. It also tends to provide more uniform answers because it is highly structured. However, mail surveys are less suitable than interviews for obtaining spontaneous answers, and they also cannot prevent respondents from reading ahead or changing earlier answers based on later information. They also cannot prevent respondents from skipping questions.

Mail questionnaires are also the best choice when the research budget is limited, a large sample size is desired, a sampling list representative of the study population is readily available, the sample is more dispersed, privacy is important, and respondents have to check other sources to give appropriate responses.

Face-to-face interviews tend to provide more usable data, but are costly, have long data collection times, require significant effort from interviewers, and yield a smaller sample size. They are an appropriate option when potential respondents cannot read and write because they offer in-person contact, and they also generally have high response rates. On the downside, face-to-face interviews can be problematic if respondents are geographically scattered because they may be difficult to locate and interview. They offer less privacy than mail or Internet surveys, but more privacy than focus groups. Face-to-face interviews afford significant interaction between interviewers and respondents, which allows interviewers to clear up seemingly inaccurate answers by restating or explaining the questions, control which individuals answer the questions, secure more spontaneous reactions, ensure that every relevant item is answered, and collect valuable supplementary information about respondents’ personal characteristics and environment. It also improves responses to open-ended questions by allowing interviewers to elicit fuller, more complete responses, and allows the use of visual aids to help explain questions. However, face-to-face interviews also require significant fieldwork training for interviewers, and pose an increased risk of interviewer- and respondent-based bias.

The length of the interaction with face-to-face interviews usually does not affect the refusal rate once respondents agree to the process, and respondents are more likely to be truthful when answering sensitive questions. This format is useful when the goal is to find out whether the respondent possesses a particular piece of knowledge or information, and it allows the interviewer to control the sequence in which questions are asked. Additionally, the completion rate for personal interviews is higher than for any other method. A disadvantage of the face-to-face interview format is that respondents generally are unable to check other sources, so it is less suitable for questions that demand more specialized knowledge. It is also less likely to provide uniform results.

Face-to-face interviews are preferred when respondents are illiterate or have little education and interviewers have to do the recording, interaction with the respondents is required, the sample size is relatively small, respondents are concentrated in a confined geographic area, the order of the questions is important, the questions are relatively complex and difficult, the questions are not so sensitive that respondents feel threatened or embarrassed about answering them, visual aids have to be used, the research instrument is relatively lengthy, and checking other sources for information is not allowed.

Telephone interviews provide more usable data and take less time to collect data, but can be costly, require significant effort, and produce a smaller sample size. They are also appropriate when respondents are dispersed across a large geographic area or have a low literacy level, and offer greater privacy than focus group interviews. Telephone interviews yield higher responses than mail surveys but lower than personal interviews. They also allow significant interaction between interviewers and respondents, which allows them to clarify misinterpretations and resolve issues that can be expressed verbally, but do not offer as much interaction as face-to-face interviews. Some other disadvantages of telephone interviews include that they do not allow the utilization of visual aids, they present some risk of bias, and they require significant training for interviewers.

The instrument used for conducting telephone interviews must be relatively short and should not include sensitive questions unless complete confidentiality is assured. Telephone interviews also tend to provide less uniform results than mail, Internet, or group surveys. However, the telephone interview format helps determine whether the respondent possesses a particular piece of information, allows the interviewer to control the sequence in which questions are asked, and tends to have high completion rates.

Telephone interviews are preferred when respondents are spread out geographically, rapid data collection is needed, the questionnaire is relatively short and easy, question sequence is important, questions are somewhat sensitive and anonymity of response is desired, no visual aid is required, respondents are not permitted to receive help in answering questions, respondents are illiterate or have little education, and the research setting is unimportant.