  MELIBEA is a Spanish database that uses a composite formula with eight
weighted conditions to estimate the effectiveness of Open Access mandates
(registered in ROARMAP). We analyzed 68 mandated institutions for publication
years 2011-2013 to determine how well the MELIBEA score and its individual
conditions predict what percentage of published articles indexed by Web of
Knowledge is deposited in each institution's OA repository, and when. We found
a small but significant positive correlation (0.18) between MELIBEA score and
deposit percentage. We also found that for three of the eight MELIBEA
conditions (deposit timing, internal use, and opt-outs), one value of each was
strongly associated with deposit percentage or deposit latency (immediate
deposit required, deposit required for performance evaluation, unconditional
opt-out allowed for the OA requirement but no opt-out for deposit requirement).
When we updated the initial values and weights of the MELIBEA formula for
mandate effectiveness to reflect the empirical association we had found, the
score's predictive power doubled (.36). There are not yet enough OA mandates to
test further mandate conditions that might contribute to mandate effectiveness,
but these findings already suggest that it would be useful for future mandates
to adopt these three conditions so as to maximize their effectiveness, and
thereby the growth of OA.
