Thursday, September 1, 2016

Why preregistration no longer makes me nervous

In a recent presidential column in the APS Observer, Susan Goldin-Meadow lays out her concerns about preregistration.  She has two main concerns:

  • The first is the fear that preregistration will stifle discovery. Science isn’t just about testing hypotheses — it’s also about discovering hypotheses grounded in phenomena that are worthy of study. Aren’t we supposed to let the data guide us in our exploration? How can we make new discoveries if our studies need to be catalogued before they are run?
  • The second concern is that preregistration seems like it applies only to certain types of studies — experimental studies done in the lab under controlled conditions. What about observational research, field research, and research with uncommon participants, to name just a few that might not fit neatly into the preregistration script?

She makes the argument that there are two stages of scientific practice, and that pre-registration is only appropriate for one of them:
The first stage is devoted to discovering phenomena, describing them appropriately (i.e., figuring out which aspects of the phenomenon define it and are essential to it), and exploring the robustness and generality of the phenomenon. Only after this step has been taken (and it is not a trivial one) should we move on to exploring causal factors — mechanisms that precede the phenomenon and are involved in bringing it about, and functions that follow the phenomenon and lead to its recurrence….Preregistration is appropriate for Stage 2 hypothesis-testing studies, but it is hard to reconcile with Stage 1 discovery studies.

I must admit that I started out with exactly the same concerns about pre-registration.  I was worried that it would stifle discovery, and lead to turnkey science that would never tell us anything new. However, I no longer believe that.  It’s become clear to me that pre-registration is just as useful at the discovery phase as at the hypothesis-testing phase, because it helps keep us from fooling ourselves.  For discovery studies, we have adopted a strategy of pre-registering whatever details we can; in some cases this might just be the sample size, sampling strategy, and the main outcome of interest.  In these cases we will almost certainly do analyses beyond these, but having pre-registered these details gives us and others more faith in the results from the planned analyses; it also helps us more clearly distinguish between a priori and ad hoc analysis decisions (i.e., we can’t tell ourselves “we would have planned to do that analysis”); if it’s not pre-registered, then it’s treated through the lens of discovery, and thus not really believed until it’s replicated or otherwise validated.  In the future, in our publications we will be very clear about which results arose from pre-registered analyses and which were unplanned discovery analyses; I am hopeful that by helping more clearly distinguish between these two kinds of analyses, the move to pre-registration will make all of our science better.

I would also argue that the phase of "exploring the robustness and generality of the phenomenon”, which Goldin-Meadow assigns to the unregistered discovery phase, is exactly the phase in which pre-registration is most important. Imagine how many hours of graduate student time and gallons of tears could have been saved if this strategy had been used in the initial studies of ego depletion or facial feedback.  In our lab, it is now standard to perform a pre-registered replication before we believe any new behavioral phenomenon; it’s been interesting to see how many of them fall by the wayside.  In some cases we simply can’t do a replication due to the size or nature of the study; in these cases, we register whatever we can up front, and we try to reserve a separate validation dataset for testing of whatever results come from our initial discovery set.  You can see an example of this in our recent online study of self-regulation.

I’m glad that this discussion is going on in the open, because I think a lot of my colleagues in the field share concerns similar to those expressed by Goldin-Meadow.  I hope that the examples of many successful labs now using pre-registration will help convince them that it really is a road to better science.