How failed replications change our effect size estimates

Yesterday I posted a very unscientific survey asking researchers to describe how failed replications changed their subjective estimates of effect sizes. The main survey asked for “ballpark estimates” of effect sizes, but an alternative interactive version allowed researchers to also report their uncertainty by specifying both the mean and variance of their posterior distributions. Thanks to everyone who participated. I won’t be analyzing any new data after this, but it’s never too late to publicly share your estimates!

Here are the questions. 

Question 1. A 2009 experiment with 50 subjects (25 per cell) is published in Psych Science. The experiment does not require any special equipment other than a questionnaire. It is not pre-registered. The results show an effect size of d=0.5. Let’s define the true effect size to be the average effect size of an infinite number of replications that the original experimenter would deem “reasonably exact” in advance. Based on this information alone, what is your ballpark subjective estimate of the true effect size?

Question 2. What if the experiment had been pre-registered? 

Question 3. Assume again that the experiment was not pre-registered. Now imagine that a pre-registered replication attempt with the same sample size estimated the effect size to be d=0.0. At the time of pre-registration, the original experimenter deemed it “reasonably exact”. Based on this replication and the original experiment, what is your ballpark subjective estimate of the true effect size?

Question 4. What if the replication attempt had 300 subjects per cell?

Here are the results.

Keeping in mind all the caveats about sampling bias and other issues, here are a few observations: