It is quite easy to get a manuscript accepted in a scientific journal if only a few basic requirements are met, i.e. a reasonably interesting research question, a sound study design, and generally acceptable results. Unfortunately, the chance of succeeding with this in a randomised trial is not great. Randomised trials are expensive, time-consuming, and require extensive knowledge of regulatory provisions and scientific guidelines. Even worse, as the outcome cannot be predicted, there may not be any return on the invested time and money.

A much more successful, simpler, cheaper and quicker alternative is to use a convenience sample, data already collected for another purpose, such as register data or a cohort of patients already studied for something else. Only two additional tasks are then required, a) to identify a couple of statistically significant differences, which usually is not difficult with access to statistical software, and b) to formulate an interesting, preferably politically correct, explanation of the observed differences. The result is a generated hypothesis. When the scientific report is written, the reasoning is just reverted. The hypothesis is presented first and the results of the statistical analysis are used to “demonstrate” that the hypothesis is correct.

This approach to scientific research is known as HARKing (1), and it is surprisingly common. One drawback of the approach is that the findings are prone to primarily reflect bias or sampling variation and can usually not be reproduced in well-design and well-performed confirmatory studies. However, many authors don’t wish to engage in reproducing results as they consider it more meritorious to generate new hypotheses.


1. Kerr NL. HARKing: hypothesizing after the results are known. Pers Soc Psychol Rev 1998;2:196-217.