The effect of open access and downloads ('hits') on citation impact: a bibliography of studies

Since 1998 studies have shown that open access increases impact as measured by the number of citations. This chronological and comprehensive bibliography of those reports provides a way of investigating the meaning of that statement, to understand its effect, to recognise the significant factors involved, and identify the causal relationships between the respective factors. Reviews in 2010 suggest a ratio of between 5.5:1 and 7:1 of studies showing an open access citation advantage against those that do not. The bibliography also lists the Web tools available to measure impact. It is a focused bibliography, on the relationship between impact and access. It does not attempt to cover citation impact, or other related topics such as open access, more generally, although some key papers in these areas are listed as jump-off points for wider study. Other important effects can be found in the area of research assessment. There is an occasionally updated section on the correlation between research access, impact and assessment. This is a snapshot of the bibliography taken towards the end June 2013. The research on this topic continues, as does the updated version of the bibliography.