The piranha problem (too many large, independent effect sizes influence the same outcome) has received some attention on Andrew Gelman’s blog. But now it’s a paper!  Chris Tosh (Memorial Sloan Kettering) talks about multiple views of the piranha problem and detecting the implausible scientific claims that are published. The butterfly effect makes an appearance. 

If you enjoyed the science-vs-pseudoscience topics, you’ll enjoy this one.

0:00 - Coming up in the episode

2:35 - What is the Piranha Problem?

19:54 - Confusing effect sizes

23:11 - The "words & walking speed" study

26:22 - Declaration of independent variables

30:58 - Piranha theorems for correlations

37:07 - Piranha theorems for linear regression

40:37 - Piranha Theorems for mutual information 

44:13 - Bounds on the independence of the covariates

46:12 - Applying the piranha theorem to real data

50:12 - Applying the piranha theorem across studies

54:05 - A Bayesian detour

1:00:12 - The butterfly effect & chaos

1:04:26 - Applying the piranha theorem to cancer research