in Goodstein’s assessment, “injecting falsehoods into the body of science is rarely, if ever, the purpose of those who perpetrate fraud. They almost always believe that they are injecting a truth into the scientific record.”

…From his investigations Goodstein found three risk factors present in nearly all cases of scientific fraud. The perpetrators, he writes, “1. Were under career pressure; 2. Knew, or thought they knew, what the answer to the problem they were considering would turn out to be if they went to all the trouble of doing the work properly; and 3. Were working in a field where individual experiments are not expected to be precisely reproducible.”

That is Scientific American on scientific fraud.

Clear-cut cases of fraud include the twin studies of British psychologist Cyril L. Burt (who faked so many twins that he had to fabricate additional twin researchers), the Sloan-Kettering Institute cancer researcher William Summerlin’s experiments on inducing healthy black skin grafts on white mice (which he was caught enhancing with a black felt-tipped pen)