Stephen T’s Blog Spot

Last time I argued that mixed methods is really about integration. There is one word that often stands in for that integration and quietly does a great deal of unearned work: triangulation. People write ‘we triangulated’ as though it settles the question of whether a finding can be trusted. By itself, it does not.

Start with what the word is doing. Triangulation is only one of several reasons to combine methods. Studying fifty-seven mixed-method evaluations in 1989, Jennifer Greene and colleagues found that researchers mix methods for at least five distinct purposes, and triangulation is just one. The others are complementarity, using one method to elaborate another; development, letting one method’s results build the other, as when interviews shape a survey; initiation, deliberately seeking contradiction to provoke insight; and expansion, using different methods for different parts of the inquiry. Many studies that claim triangulation are actually doing one of these four. Naming the purpose honestly tells you what convergence would even mean.

Now the condition almost everyone skips. Triangulation, in its strict sense, means using more than one method to study the same phenomenon and looking for convergence, in order to cancel out the bias of any single method. The logic depends entirely on independence. It only works if the methods have different weaknesses, so that their errors do not line up. Two methods that share a bias do not corroborate each other; they reinforce the same mistake. If your survey and your interviews both depend on people remembering accurately and answering honestly, their agreement is comforting and may still be wrong. Convergence from methods that share a blind spot is not validation. It is an echo.

There is also a quieter confusion at work, and it is the most common one. When you use a survey and a set of interviews to study the same thing, you are often not measuring the same thing at all. The survey captures how often; the interviews capture why, and how it feels. Those are different facets, and they will not converge, because they were never aimed at the same point. Expecting them to agree, and fretting when they do not, mistakes complementarity for triangulation. The two methods are handing you a fuller picture, not a second opinion on the same number.

And when methods genuinely are aimed at the same target and still disagree, that is not a failure to be smoothed away. As I have said before, the disagreement is often the most informative thing you have. It can mean one method is biased, or that the phenomenon is more complicated than either method alone would suggest. Greene’s framework even gives the deliberate pursuit of that tension a name: initiation.

So ‘we triangulated’ should not function as a verbal stamp of validity. The useful questions are sharper than that. Were the methods actually aimed at the same construct, or at different facets of it? Did they carry independent weaknesses, or the same blind spot? And if they diverged, what is that divergence telling you? Answer those, and triangulation becomes a real instrument for strengthening an inference. Skip them, and it is just a reassuring word in a methods section.

For those of us in evaluation, triangulation is almost a reflex in a proposal. The discipline is to make it mean something. Say which methods are converging on which construct, explain why their weaknesses are independent, and state what you will do if they disagree. That is the line between triangulation as a method and triangulation as decoration.

So here is my question: When you see triangulation claimed in a study, do you check whether the methods were truly independent and aimed at the same thing, or has the word become a stamp that gets applied whenever more than one method is in the room?