ABSTRACT
This chapter has had around 3 million views and 3,500 citations; a real citation classic. One of the most important pillars of science is that a study should give essentially the same results when repeated by the original authors or reproduced by other scientists, i.e. the results should be reproducible. Nearly 30,000 journals publish around 2 million scientific papers annually and the number of papers is growing at an annual rate of 3.3%, i.e. doubling every 20 years. Career advancement in science usually depends upon publication of research papers, especially first authorship on papers in a high-impact journal. In a well-designed study, a researcher would decide on number of observations or repetitions that they are going to make during planning stage of a study. Ioannidis suggested that research findings are more likely to be true in fields that undertake large studies such as randomised controlled trials with several thousand subjects and less likely to be true in smaller studies.
