The “file-drawer problem” consists of researchers not publishing their p>.05 studies (Rosenthal 1979 .htm). P-hacking consist of researchers not reporting their p>.05 analyses for a given study. P-hacking is easy to stop. File-drawering nearly impossible. Fortunately, while p-hacking is a real problem, file-drawering is not. Consequences of p-hacking vs file-drawering With p-hacking it’s easy to…
Author: Uri Simonsohn
[54] The 90x75x50 heuristic: Noisy & Wasteful Sample Sizes In The “Social Science Replication Project”
An impressive team of researchers is engaging in an impressive task: Replicate 21 social science experiments published in Nature and Science in 2010-2015 (.htm). The task requires making many difficult decisions, including what sample sizes to use. The authors' current plan is a simple rule: Set n for the replication so that it would have 90%…
[52] Menschplaining: Three Ideas for Civil Criticism
As bloggers, commentators, reviewers, and editors, we often criticize the work of fellow academics. In this post I share three ideas to be more civil and persuasive when doing so. But first: should we comment publicly in the first place? One of the best known social psychologist, Susan Fiske (.htm), last week circulated a draft of an invited opinion…
[51] Greg vs. Jamal: Why Didn’t Bertrand and Mullainathan (2004) Replicate?
Bertrand & Mullainathan (2004, .htm) is one of the best known and most cited American Economic Review (AER) papers [1]. It reports a field experiment in which resumes given typically Black names (e.g., Jamal and Lakisha) received fewer callbacks than those given typically White names (e.g., Greg and Emily). This finding is interpreted as evidence of racial discrimination…
[50] Teenagers in Bikinis: Interpreting Police-Shooting Data
The New York Times, on Monday, showcased (.htm) an NBER working paper (.pdf) that proposed that “blacks are 23.8 percent less likely to be shot at by police relative to whites.” (p.22) The paper involved a monumental data collection effort to address an important societal question. The analyses are rigorous, clever and transparently reported. Nevertheless, I do…
[48] P-hacked Hypotheses Are Deceivingly Robust
Sometimes we selectively report the analyses we run to test a hypothesis. Other times we selectively report which hypotheses we tested. One popular way to p-hack hypotheses involves subgroups. Upon realizing analyses of the entire sample do not produce a significant effect, we check whether analyses of various subsamples — women, or the young, or republicans, or…
[47] Evaluating Replications: 40% Full ≠ 60% Empty
Last October, Science published the paper “Estimating the Reproducibility of Psychological Science” (htm), which reported the results of 100 replication attempts. Today it published a commentary by Gilbert et al. (.htm) as well as a response by the replicators (.htm). The commentary makes two main points. First, because of sampling error, we should not expect all of…
[43] Rain & Happiness: Why Didn’t Schwarz & Clore (1983) ‘Replicate’ ?
In my “Small Telescopes” paper, I introduced a new approach to evaluate replication results (SSRN). Among other examples, I described two studies as having failed to replicate the famous Schwarz and Clore (1983) finding that people report being happier with their lives when asked on sunny days. Figure and text from Small Telescopes paper (SSRN) I…
[42] Accepting the Null: Where to Draw the Line?
We typically ask if an effect exists. But sometimes we want to ask if it does not. For example, how many of the “failed” replications in the recent reproducibility project published in Science (.pdf) suggest the absence of an effect? Data have noise, so we can never say ‘the effect is exactly zero.’ We can…
[41] Falsely Reassuring: Analyses of ALL p-values
It is a neat idea. Get a ton of papers. Extract all p-values. Examine the prevalence of p-hacking by assessing if there are too many p-values near p=.05. Economists have done it [SSRN], as have psychologists [.html], and biologists [.html]. These charts with distributions of p-values come from those papers: The dotted circles highlight the excess of…