Chapter 11: Introduction to Interviewing Techniques

Prepared for the Interdisciplinary and Global Studies Division,
Worcester Polytechnic Institute
by James K. Doyle
Associate Professor
Department of Social Science and Policy Studies

Standardized Interviews

The design, implementation, and analysis of standardized interviews are very similar to that of mail and telephone surveys (although the increased personal contact between the researcher and the participants adds another layer of complication). The treatment of standardized interviews in this monograph is therefore relatively brief, and readers are referred to the relevant sections of the IGSD document titled "Introduction to Survey Design and Methodology" when appropriate (hereinafter referred to as the IGSD Survey Manual). For example, Section V of the IGSD Survey Manual discusses how to choose from among the three main types of standardized surveys.

A. Selecting Participants

Since the main goal of standardized interviews is to provide answers to questions that can be generalized to larger groups of people beyond the interview study, participants should be sampled randomly from the population of interest.

This requires the construction of an unbiased list of members of the target population and an unbiased decision rule for selecting people from the list to interview. The technique of simple random sampling is described in Section III of the IGSD Survey manual.

In addition to choosing participants randomly, a strong effort must be made to ensure that a high percentage of people selected in the random sample actually end up participating. That is, you must achieve a high "response rate" to your requests for interviews. The importance of high response rates and techniques for achieving them are described in Section IV of the IGSD Survey Manual.

B. Deciding How Many Interviews to Conduct

Standardized interviews are designed to allow for results to be tested for statistical significance. Thus a comparatively large number of people must be interviewed. The number of interviews conducted in a standardized survey is not flexible, as it is in a qualitative interview, but should be determined before data collection begins. This is because, while adding people to the study at a late date increases the sample size, it typically decreases the response rate below acceptable limits.

Choosing on an exact number of standardized interviews to conduct requires a statistical calculation that depends on the degree of variation in the population and how much sampling error is acceptable. Directions for making this calculation appear in Section III of the IGSD Survey Manual.

C. Preparing to Interview

To achieve standardization in an interview requires a great deal of advance preparation. The entire interview, including introductory comments, must be scripted, and even those aspects of the interview which can't be anticipated, such as the need to answer requests for clarification, must be standardized as much as possible. Writing valid, reliable, and unbiased standardized survey questions and organizing them into an effective interview script is a complicated art and success can only be achieved by subjecting the script to a rigorous process of review and revision. Tips for writing good questionnaires can be found in Section VI of the IGSD Survey manual. Sections VII and VIII of that document also discuss questionnaire design and pretesting, respectively.

A carefully constructed interview script, however, is necessary but not sufficient to prepare to conduct standardized interviews. The style and quality of delivery by the interviewer can influence how people answer the questions, and therefore the delivery must be uniform across participants. This means that, before data collection begins, interviewers should practice reading the script until they can deliver it with consistent quality, emphasis, and pacing.

D. The Interview Process

The researcher's goal during a standardized interview should be to say as little as possible, other than reading the interview script exactly as it is written. This requires, for example, that even when a participant has answered a question as part of a previous answer, the question must be read and answered again. Also, if a participant begins to volunteer an answer before the entire question is read, they should be asked to wait until they've heard the entire question.

Of course, deviations from the interview script are often necessary to provide clarification or feedback to the participant or to probe for more detail when the answers are too general to be useful. Suggestions for accomplishing these tasks while ensuring standardization are detailed below:

Clarification. The first strategy to try when participants ask for a question to be clarified is simply to repeat all or part of the question. If this doesn't work, the interviewer should be able to draw upon a prepared list of definitions and stock answers to frequently asked questions.
Feedback. It is important for the interviewer to provide their subjects feedback when they are doing well in order to encourage them to listen carefully and to give thoughtful answers. This feedback may be in the form of a nonverbal smile or nod or a short encouraging phrase. Verbal feedback should be selected from a prepared list of stock phrases such as "That's useful information" or "That's the type of answer we're looking for" or "Thank you, that's helpful" to ensure that the feedback is uncorrelated with the content of what the participant is saying. However, care should be taken to ensure that positive feedback is given only for satisfactory performance.
Probing. If a participant's performance is unsatisfactory, the interviewer must employ unbiased techniques to encourage answers that are more complete, appropriate, and thoughtful. These strategies of "probing" for more information may be just a pregnant pause to encourage the person to fill the silence or a direct request for further information. Verbal probes should, like feedback phrases, be chosen from a stock list of phrases such as "Could you explain what you mean by that?" or "Can you tell me anything else about ___________ ?"

E. Reducing and Analyzing the Data

Data reduction is much less of an issue for standardized interviews than for qualitative interviews, since much less data are collected. Standardized interviews generally ask questions that call for relatively short, simple, or quantifiable answers which the interviewer writes or marks on a copy of the interview script during the interview. So long as the interviewer takes the time to write everything down accurately (including any probes or other deviations from the interview script), it is not usually necessary to record the interview sessions.

The main goal in the analysis of standardized interview data is to quantify the data and subject it to statistical analysis so that hypotheses can be confirmed or disconfirmed and the degree of error associated with population estimates can be determined. An introduction to this process of statistical data analysis can be found in Section XII of the IGSD Survey Manual.

For Further Information

This paper has described the basic steps of planning, implementing, and analyzing three different types of interview studies that are appropriate in different situations: qualitative interviews, focus groups, and standardized interviews. However, if you choose to adopt one of these methods as part of your IQP, you should also seek out additional information on the method you have selected. The following sources are recommended as good places to begin this learning process:

A. Qualitative Interviewing

Rubin, H. J., and Rubin, I. S. (1995). Qualitative Interviewing: The Art of Hearing Data. Thousand Oaks, CA: Sage.

Seidman, I. E. (1998). Interviewing as Qualitative Research: A Guide for Researchers in Education and the Social Sciences, 2nd ed.. New York: Teacher's College Press.

Steinar, K. (1996). Interviews: An Introduction to Qualitative Research Interviewing. Thousand Oaks, CA: Sage.

B. Focus Groups

Goldman, A. E., and McDonald, S. S. (1987). The Group Depth Interview: Principles and Practices. Englewood Cliffs, NJ: Prentice-Hall.

Krueger, R. A. (1998). Moderating Focus Groups. Thousand Oaks, CA: Sage.

Morgan, D. L. (1997). Focus Groups as Qualitative Research, 2nd ed. Thousand Oaks, CA: Sage.

Morgan, D. L. (1998). Planning Focus Groups. Thousand Oaks, CA: Sage.

C. Standardized Interviews

Fowler, F. J. (1990). Standardized Survey Interviewing: Minimizing Interviewer-Related Error. Newbury Park, CA: Sage.

Salant, P. A., and Dillman, D. A. (1994). How to Conduct Your Own Survey. New York: Wiley.

Survey Research Center (1983). General Interviewing Techniques: A Self-Instructional Workbook for Telephone and Personal Interviewer Training. University of Michigan, Ann Arbor: Survey Research Center.

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Last modified: November 09, 2006 11:49:23