About replication. See replication crisis. From the authorized english translation by Nicholas J.L. Brown available as a free download in PDF format

Clearly, there was something in the recipe for the X effect that I was missing. But what? I decided to ask the experts, the people who’d found the X effect and published lots of articles about it [..] My colleagues from around the world sent me piles of instructions, questionnaires, papers, and software [..] In most of the packages there was a letter, or sometimes a yellow Post-It note stuck to the bundle of documents, with extra instructions: “Don’t do this test on a computer. We tried that and it doesn’t work. It only works if you use pencil-and-paper forms.” “This experiment only works if you use ‘friendly’ or ‘nice’. It doesn’t work with ‘cool’ or ‘pleasant’ or ‘fine’. I don’t know why.” “After they’ve read the newspaper article, give the participants something else to do for three minutes. No more, no less. Three minutes, otherwise it doesn’t work.” “This questionnaire only works if you administer it to groups of three to five people. No more than that.” I certainly hadn’t encount

From his memoirs: "Ontsporing" (English, "Derailment") Nov. 2012