India, Aug. 13 -- At 11.47 pm, a scientist in California compares two cancer research papers. They come from different labs and claim to study different things, but one image in each is identical. She checks it against her database of suspicious cases and finds the same image-flipped and relabelled-in four more papers. All of them have been published in peer-reviewed scientific journals.

A new study in Proceedings of the National Academy of Sciences, led by Reese Richardson at Northwestern University with Luis Amaral and Jennifer Byrne, maps the scale of what these fraud detectives are up against. The team analysed millions of journal records, retractions, and post-publication critiques to detect statistical "footprints" of scientific fr...