  Publication selection bias undermines the systematic accumulation of
evidence. To assess the extent of this problem, we survey over 68,000
meta-analyses containing over 700,000 effect size estimates from medicine
(67,386/597,699), environmental sciences (199/12,707), psychology (605/23,563),
and economics (327/91,421). Our results indicate that meta-analyses in
economics are the most severely contaminated by publication selection bias,
closely followed by meta-analyses in environmental sciences and psychology,
whereas meta-analyses in medicine are contaminated the least. After adjusting
for publication selection bias, the median probability of the presence of an
effect decreased from 99.9% to 29.7% in economics, from 98.9% to 55.7% in
psychology, from 99.8% to 70.7% in environmental sciences, and from 38.0% to
29.7% in medicine. The median absolute effect sizes (in terms of standardized
mean differences) decreased from d = 0.20 to d = 0.07 in economics, from d =
0.37 to d = 0.26 in psychology, from d = 0.62 to d = 0.43 in environmental
sciences, and from d = 0.24 to d = 0.13 in medicine.
