Friday, April 13, 2012

Is It Possible, In Principle, To Do Methodologically Sound Research?

In a paper published 31 years ago, Joseph McGrath argues (html, pdf) that the answer is no. Specifically, he claims that any research design faces two trade-offs: 1) being obtrusive vs unobstrusive (which maps to my terminology as acquiring info vs altering subject), and 2) being generalizable vs context-cognizant (which maps to my terminology as precision vs simplicity).

In his terminology, these trade-offs allow for the optimization of three distinct values (generalizability of samples to populations; precision in measuring variables; and context realism for the participants). Initially, I disagreed with this. To me, intuition suggests that there should be four points which maximize certain qualities when you are considering the intersection of two-trade offs: one in each corner of the 2-d space.

One way to get around this is if you claim that, in the context of this decision (study design), the trade-offs are not independent. For example, it might be very difficult for a design to be both highly generalizable and highly obstrusive.

Below I've drawn an example. Think of the dots as realizations of actually feasible study designs sampled from someone's mental generation process; i.e., they are probably not at the absolute extremes of the theoretical distribution, but with enough realizations, would come close.

I'm not sure that I agree with this exact distribution, and it would need some justification, but it seems like the only way to justify his three-pronged rather than four-pronged set-up.