Advantages of Interview and Questionnaire

    Before
developing questions, researchers need to decide whether to collect data
through interviews or questionnaires. Each method has advantages and
disadvantages.

Advantages
of Questionnaires

    Self-administered
questionnaires, which can be distributed in person, by mail, or over the
Internet, offer some advantages. The strengths of questionnaires include the
following:

    1:Cost.
Questionnaires, relative to interviews, are in general much less costly and
require less time and energy to administer. Distributing questionnaires to
groups (eg, to students in a classroom) is clearly an inexpensive and expedient
approach. And, with a fixed amount of funds or time, a larger and more
geographically diverse sample can be obtained with mailed or web-based
questionnaires than with interviews.

    2:Anonymity.
Unlike interviews, questionnaires offer the possibility of complete anonymity.
A guarantee of anonymity can be crucial in obtaining candid responses,
particularly if the questions are personal or sensitive. Anonymous
questionnaires often result in a higher proportion of socially unacceptable
responses (ie, responses that place respondents in an unfavorable light) than
interviews. 

    Interviewer bias. The absence of an interviewer ensures that
there will be no interviewer bias. Interviewers ideally are neutral agents
through whom questions and answers are passed. Studies have shown, however,
that this ideal is difficult to achieve. Respondents and interviewers interact
as humans, and this interaction can affect responses.

    Web-based
surveys are especially economical, and can yield a data set directly amenable
to analysis, without having to have staff entering data (the same is also true
for CAPI and CATI interviews). Internet surveys also provide opportunities for
interactively providing participants with customized feedback, and for prompts
that can minimize missing responses.

Advantages
of Interviews

    The
strengths of interviews far outweigh those of questionnaires. It is true that
interviews are costly, prevent respondent anonymity, and bear the risk of
interviewer bias. However, interviews are considered superior to questionnaires
for most research purposes because of the following advantages:

    1:Response
rates. Response rates tend to be high in face-to-face interviews. People are
more reluctant to refuse to talk to an interviewer who directly requests their
cooperation than to discard or ignore a questionnaire. A well-designed and
properly conducted interview study normally achieves response rates in the
vicinity of 80% to 90%, whereas mailed and web-based questionnaires typically
achieve response rates of 50% or lower. 

    Because nonresponse is not random, low
response rates can introduce serious biases. (However, if questionnaires are
personally distributed to people in a particular setting—eg, maternity patients
about to be discharged from the hospital—reasonably good response rates can be
achieved.)

    2:Audience.
Many people simply cannot fill out a questionnaire. Examples include young
children and blind, elderly, illiterate, or uneducated individuals. Interviews,
on the other hand, are feasible with most people. For web-based questionnaires,
a particularly important drawback is that not everyone has access to computers
or uses them regularly even if they do.

    3:Clarity.
Interviews offer some protection against ambiguous or confusing questions.
Interviewers can determine whether questions have been misunderstood and can
clarify matters. In questionnaires, misinterpreted questions can go undetected
by researchers, and thus responses may lead to erroneous conclusions.

    4:Depth
of questioning. The information obtained from questionnaires tends to be more
superficial than interview data, largely because questionnaires typically
contain mostly closed-ended items. Open-ended questions are avoided in
questionnaires because most people dislike having to compose and write out a
reply. 

    Much of the richness and complexity of respondents’ experiences are lost
if closed-ended items are used exclusively. Furthermore, interviewers can
enhance the quality of self-report data through probing.

    5:Missing
information. Respondents are less likely to give “don’t know” responses or to
leave a question unanswered in an interview than on questionnaires.

    6:Order
of questions. In an interview, researchers have control over question ordering.
Questionnaire respondents are at liberty to skip around from one section of the
instrument to another. It is possible that a different ordering of questions
from the one originally intended could bias responses.

    7:Sample
control. Interviews allow greater control over the sample. Interviewers know
whether the people being interviewed are the intended respondents. People who
receive questionnaires, by contrast, can pass the instrument on to a friend,
relative, and so forth, and this can change the sample composition. 

    Web-based
surveys are especially vulnerable to the risk that people not targeted by
researchers will respond, unless there are password protections.

    8:Supplementary
data. Finally, face-to-face interviews can result in additional data through
observation. Interviewers are in a position to observe or judge the
respondents’ level of understanding, degree of cooperativeness, social class,
lifestyle, and so forth. Such information can be useful in interpreting
responses. 

    Many advantages of face-to-face interviews also apply to telephone
interviews. Long or detailed interviews or ones with sensitive questions
usually are not well suited for telephone administration, but for relatively
brief instruments, telephone interviews are more economical than personal
interviews and tend to yield a higher response rate than mailed questionnaires.