Triangulation
research-methodology
Triangulation is the use of multiple data sources, methods, researchers, or theoretical perspectives to study the same phenomenon. The logic is convergence: if different approaches yield consistent findings, confidence in the results increases. If they diverge, the discrepancy itself is analytically productive.
Denzin's Four Types
Norman Denzin (1978) identified four types of triangulation, which remain the standard typology:
| Type | Description | SLA example |
|---|---|---|
| Data triangulation | Multiple data sources (different times, settings, or participants) | Collecting data from beginners, intermediates, and advanced learners |
| Investigator triangulation | Multiple researchers analyse the same data | Two coders independently coding Corrective Feedback episodes |
| Theoretical triangulation | Multiple theoretical frameworks applied to the same data | Interpreting classroom interaction through both sociocultural and cognitive lenses |
| Methodological triangulation | Multiple methods used in the same study | Combining test scores with interviews and Classroom Observation |
Denzin further distinguished within-method triangulation (using multiple scales within a questionnaire) from between-method triangulation (combining quantitative and qualitative methods — essentially Mixed Methods Research).
Purpose
Triangulation serves different purposes depending on the research paradigm:
- In post-positivist research: convergent results increase confidence that findings are "true" (closer to traditional validity)
- In interpretivist research: multiple perspectives enrich understanding without claiming one objective truth
- In critical research: different data sources can reveal contradictions between what participants say and what they do
In Applied Linguistics
Triangulation is particularly valued in:
- Classroom-based Research — test scores alone cannot explain classroom dynamics; adding interviews and observation creates a fuller picture
- Teacher Cognition research — comparing what teachers say in interviews with what they do in observed lessons (Teacher Beliefs vs practice)
- Assessment validation — multiple evidence sources for Construct Validity
- Action Research — teachers triangulate data from student work, observations, and reflections
Cautions
- Triangulation does not guarantee validity — if all methods share the same bias, convergence is misleading
- Divergent findings are not necessarily a problem; they may reveal complexity
- The term is sometimes used loosely to mean "I used multiple methods" without genuine integration of findings
Key References
- Denzin (1978) — The Research Act (four types of triangulation)
- Lincoln & Guba (1985) — triangulation as a credibility strategy in Qualitative Research
- Creswell & Miller (2000) — validity procedures in qualitative research including triangulation