Policies ensuring that research data are available on public archives are increasingly
being implemented at the government [1], funding agency [2-4], and journal [5, 6]
level. These policies are predicated on the idea that authors are poor stewards of
their data, particularly over the long term [7], and indeed many studies have found
that authors are often unable or unwilling to share their data [8-11]. However, there
are no systematic estimates of how the availability of research data changes with
time since publication. We therefore requested data sets from a relatively homogenous
set of 516 articles published between 2 and 22 years ago, and found that availability
of the data was strongly affected by article age. For papers where the authors gave
the status of their data, the odds of a data set being extant fell by 17% per year.
In addition, the odds that we could find a working e-mail address for the first, last,
or corresponding author fell by 7% per year. Our results reinforce the notion that,
in the long term, research data cannot be reliably preserved by individual researchers,
and further demonstrate the urgent need for policies mandating data sharing via public
archives.
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