The Value of Interviewing on Multiple Occasions or Longitudinally

Introduction

This chapter addresses issues relating to multiple interviews and interviewing across a period of time during the course of a lengthy program of research. This poses questions about researchers' relationships with both the research participants and the data they provide, especially about matters of trust and rapport in long-term engagements in the field. The focus is on qualitative research designs organized around the longitudinal collection of interview data from cohort samples. Anne Grinyer's research program about cancer in teenagers and young adults provides the case study used here; it illuminates the pragmatic and theoretical issues for interview research relating to studies with a longitudinal dimension. Grinyer's program is one example of a recent trend to mount qualitative longitudinal studies, a much larger example in the United Kingdom being the Timescapes program (2007–2012), funded by the Economic and Social Research Council. This multicenter study explores how personal relationships and identities unfold through the life course and involves core projects that follow the lives of 400 people—using in-depth interviews together with other qualitative research methods:

Whatever the scale and topic of interviewing on multiple occasions or across a lengthy period of time, the purpose is to obtain interviewees' interpretations of their own experiences and understanding of the world in which they live—as these move forward.

Advantages and Disadvantages of the Longitudinal Approach

When 20th-century social scientists were relatively new to interviewing techniques, the coupling of “interviews and longitudinal study” seemed to represent a contradiction in terms. Going back to Black and Champion (1976, p. 355), the interview was defined as “a fleeting, momentary experience” based on a one-off encounter, and it thus involved a transitory relationship between interviewer and interviewee. Longitudinal research projects were commonly associated with quantitative studies using statistically representative samples and cohort panels in large repeat surveys deploying either “tick the box” self-completion questionnaires or structured interview questionnaires administered and analyzed by research staff. Repeat questionnaire engagements with members of samples or panels were designed to capture temporal changes in lives and social contexts. However, methodological developments in favor of mixed methods showed that longitudinal research could “build a bridge” between quantitative and qualitative methods by employing both extensive and intensive approaches in a staged design (Robson, 1993; Ruspini, 2000, p. 3).

Longitudinal research, whether quantitative or qualitative, can pose particular challenges. For example, studies based on returning to the same participants face the problem of sample attrition: Some participants cannot be traced because they have moved location, may have become unable to commit to long-term participation for lifestyle reasons, may have become too ill to see another interview through, or may have died. In addition, there is the risk that some participants may regret becoming involved and decide to limit or purposively distort their responses in subsequent interviews; and another limitation may simply be recall bias (Ruspini, 2000). Such studies are also demanding of the time and resources of the researchers and are subject to the changed priorities of funders (Robson, 1993, p. 50).

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