We frequently hear qualitative researchers say that they achieve rigor through “triangulation.” Triangulation is, indeed, one of the most persuasive and powerful of techniques for assuring an audience of the reliability and credibility of qualitative research. What does this actually mean, however, and how do you do it well rather than haphazardly or poorly?
First, it’s important to be clear that there are two broad ways of “triangulating.”
1. Triangulate using different methods. In this, the researcher seeks the same information through different methods and if s/he finds the same results, this is evidence that the results are probably credible. Ex: you want to know whether violence against women is a problem in a village. You ask the question in individual interviews, focus groups, and look for evidence in previous studies/secondary data. You might also triangulate methods on the same informant in the context of the same method: for example, during a semi-structured interview, you might ask a purely open ended question about violence against women and then, later, ask the respondent to rate the extent of violence against women on a 10 point scale. When the two seem to dovetail, it’s a useful form of triangulation that gives you some insights into the validity of your data with that one informant.
2. Triangulate using different information sources. In this, the researcher seeks the same information from different sources. Ex: you want to know whether violence against women is a problem in a village. You ask the question in interviews with different categories of respondents.
To triangulate in persuasive ways, your audience needs to know
a) What assurance is there that you asked the question in similar/parallel ways to multiple informants?
b) how deep/detailed the triangulation was. Did all respondents say the same thing, or just two of them? Did all methods lead to the same conclusions, or just two of them?