Abstract
Improving the methodological rigour and the quality of data analysis in manuscripts submitted to journals is key to ensure the validity of scientific claims. However, there is scant knowledge of how manuscripts change throughout the review process in academic journals. Here, we examined 27 467 manuscripts submitted to four journals from the Royal Society (2006-2017) and analysed the effect of peer review on the amount of statistical content of manuscripts, i.e. one of the most important aspects to assess the methodological rigour of manuscripts. We found that manuscripts with both initial low or high levels of statistical content increased their statistical content during peer review. The availability of guidelines on statistics in the review forms of journals was associated with an initial similarity of statistical content of manuscripts but did not have any relevant implications on manuscript change during peer review. We found that when reports were more concentrated on statistical content, there was a higher probability that these manuscripts were eventually rejected by editors.