You asked me what my experience is with survey design. I was married to a political scientist who studied education, race and identity and learned from her about the complexities of creating a valid survey that yielded usable results.
So not an expert at all but I have developed an eye to what seems like good (as in provides usable data) vs. bad (as in muddled conceptual development of what is being studied, the limits of what is being studied and so on, which may threaten usable results) survey design.
You were indeed clear on the particular population that was being studied - current committed couples with other partners - in the description of the study. However what I noticed is that there was no separation, no acknowledgement that that population represented only a portion of a wider community. I think language something like 'We are studying
a subset of polyamorous relationships for the purpose of [fill in blank]' would have gone a long ways towards alleviating my concerns.
I am well aware it is incredibly difficult, maybe impossible, to design a survey that would capture information about an entire range of a given community. It would take years, lots of money and deep institutional pockets (like the U.S. Census Bureau or long established think tanks). I know that surveys - in order to get good data - have to select down to a narrow focus. That's the nature of the beast. So I never expected this survey to be able to do more than look at a portion of the community. I also know that surveys sometimes have to decide if they want to look at identities held by given population or the actual behavior of those populations (the two are often not similar at all!).
I was very pleased to see the further discussion of the purpose behind the survey. (I also know that this disclosure can possibly alter the results so I appreciate the decision to tell us.) From that perspective the design of the survey makes more sense.
The place of the couple in poly is pretty fraught. It is a basic unit of society. As such it has a lot of expectations, assumptions, weight and privilege. (Google 'couple privilege' if you are not already familiar with that phrase. It will be immensely helpful to you professionally to think about the implications on your clients.) And that weight poses challenges to people, both in existing dyads and those who want to date people in dyads, or are open to partners creating new dyads. Yet, we also remind folks who post here asking for help that poly relationships are at their core, related sets of dyads. For example, a triad where all three partners are involved with each other has multiple dyadic relationships that all need care, attention and focus. Poly doesn't actually collapse dyads into something else - it typically expands and alters them. So that was a long winded way to say that focusing on dyads makes sense to study at least a part of the poly population.
We also don't really know who makes up the poly population, or even what the majority of relationship structures might be. I suspect that outside of this forum (which is not a random sample!
) more people do some form of hierarchical polyamory.
And yes the words you use - primary, etc. - will have different and have varying meanings within poly cultures - and we often don't agree on the meanings ourselves. And that meaning may not align with a more 'mainstream' understanding of that word at all. I don't know how you would resolve that, except by noting that it exists and start thinking about how it might shape your data.