  Articles are cited for different purposes and differentiating between reasons
when counting citations may therefore give finer-grained citation count
information. Although identifying and aggregating the individual reasons for
each citation may be impractical, recording the number of citations that
originate from different article sections might illuminate the general reasons
behind a citation count (e.g., 110 citations = 10 Introduction citations + 100
Methods citations). To help investigate whether this could be a practical and
universal solution, this article compares 19 million citations with DOIs from
six different standard sections in 799,055 PubMed Central open access articles
across 21 out of 22 fields. There are apparently non-systematic differences
between fields in the most citing sections and the extent to which citations
from one section overlap with citations from another, with some degree of
overlap in most cases. Thus, at a science-wide level, section headings are
partly unreliable indicators of citation context, even if they are more
standard within individual fields. They may still be used within fields to help
identify individual highly cited articles that have had one type of impact,
especially methodological (Methods) or context setting (Introduction), but
expert judgement is needed to validate the results.
