I'm teaching a new course this semester: Case Studies in Statistical and Computational Modeling. The idea is to revisit published papers and the associated data and code from the paper, and p-hack the paper creatively to get whatever result you like. Yesterday I demonstrated that we could conclude whatever we liked from a recent paper that we had published; all conclusions (effect present, effect absent) were valid under different assumptions! The broader goal is to demonstrate how researcher degrees of freedom play out in real life.
Then someone asked me this question in the class:
Is it possible to write an honest psycholinguistics paper?
The short answer is: yes, but you have to accept that some editors will reject your paper. If you can live with that, it's possible to be completely honest.
Usually, the only way to get a paper into a major journal is to make totally overblown claims that are completely unsupported or only very weakly supported by the data. If your p-value is 0.06 but you want to claim it is significant, you have several options: mess around with the data till you push it below 0.05. Or claim "marginal significance". Or you can bury that result and keep redoing the experiment till it works. Or run the experiment till you get significance. There are plenty of tricks out there.
If you got super-duper low p-values, you are on a good path to a top publication; in fact, if you have any significant p-values (relevant to the question or not) you are on a good path to publication, because reviewers are impressed with p<0.05 somewhere, anywhere, in a table. That's why you will see huge tables in psychology articles, with tons and tons of p-values; the sheer force of low p-values spread out over a gigantic table can convince the reviewer to accept the paper, even though only a single cell among dozens or hundreds in that table is actually testing the hypothesis. You can rely on the fact that nobody will think to ask whether power was low (the answer is usually yes), and how many comparisons were done.
Here are some examples of successes and failures, i.e., situations where we honestly reported what we found and were either summarily rejected or (perhaps surprisingly) accepted.
For example, in the following paper,
Shravan Vasishth, Daniela Mertzen, Lena A. Jäger, and Andrew Gelman. The statistical significance filter leads to overoptimistic expectations of replicability. Journal of Memory and Language, 103:151-175, 2018.
I wrote the following conclusion:
"In conclusion, in this 100-participant study we don’t see any grounds for claiming an interaction between Load and Distance. The most that we can conclude is that the data are consistent with memory-based accounts such as the Dependency Locality Theory (Gibson, 2000), which predict increased processing difficulty when subject-verb distance is increased. However, this Distance effect yields estimates that are also consistent with our posited null region; so the evidence for the Distance effect cannot be considered convincing."
Normally, such a tentative statement would lead to a rejection. E.g., here is a statement in another paper that led to a desk rejection (same editor) in the same journal where the above paper was published:
"In sum, taken together, Experiment 1 and 2 furnish some weak evidence for an interference effect, and only at the embedded auxiliary verb."
We published the above (rejected) paper in Cognitive Science instead.
Lena A. Jäger, Daniela Mertzen, Julie A. Van Dyke, and Shravan Vasishth. Interference patterns in subject-verb agreement and reflexives revisited: A large-sample study. Journal of Memory and Language, 111, 2020.
In the above paper, we were pretty clear about the fact that we didn't manage to achieve high enough power even in our large-sample study: Table A1 shows that for the critical effect we were studying, we probably had power between 25 and 69 percent, which is not dramatically high.
There are many other such examples from my lab, of papers accepted despite tentative claims, and papers rejected because of tentative claims. In spite of the rejections, my plan is to continue telling the story like it is, with a limitations section. My hope is that editors will eventually understand the following point:
Almost no paper in psycholinguistics is going to give you a decisive result (it doesn't matter what the p-values are). So, rejecting a paper on the grounds that it isn't reporting a conclusive result is based on a misunderstanding about what we learnt from that paper. We almost never have conclusive results, even when we claim we do. Once people realize that, they will become more comfortable accepting more realistic conclusions from data.
No comments:
Post a Comment