In the Reproducibility Project, effects that were successfully replicated were generally smaller or weaker than the effects reported in the original studies.
Sources
- A reproducibility crisis? - American Psychological Association (apa.org)
- https://www.science.org/doi/10.1126/science.aac4716 (science.org)
- https://www.bps.org.uk/research-digest/what-happened-when-psychologists-tried-replicate-100-previously-published-findings (bps.org.uk)
- https://link.springer.com/article/10.3758/s13428-017-0967-6 (link.springer.com)