4.2 Research by Usage
Research on publication downloads and other usage metrics is an emerging topic within the bibliometric community, and it is increasingly proposed as a proxy for research awareness. Whereas citation measures take time to accrue, usage metrics have the potential to provide almost immediate insights into developing research areas and trends.29 The number of publication downloads30 from a particular field, institution or country may be interpreted as representing the interest in and use of research.
This report uses full text article download data from Elsevier’s ScienceDirect database, which provides approximately 20 percent of the world’s published journal articles, to offer another perspective on how an institution’s research is being used around the world.
Similar to citations, downloads tend to go down in more recent years because recent publications have not had time to accumulate enough downloads. So, this report first normalizes the number of downloads an entity receives to its publications by the total number of downloads of all U.S. publications in a given year—this is called an entity’s national download share. Then, since entities that produce more research output in general will have higher counts of downloads of that output, this report compares the entity’s national download share to its corresponding national publication share (the number of publications an entity produces divided by the number of all U.S. publications in a given year).
As Figure 4.4 shows, for most states, there is a strong correlation between their national download share and their national publication share, indicating that their share of all downloads globally is similar to their share of all publications globally. What about those that deviate from the trend?
Massachusetts and Maryland are above the trend line (the ratios of their national download share to publication share were 1.21 and 1.30, respectively). This means that their publications were downloaded more often than could be expected based on their volume of publications.
Across all of Maryland’s research outputs, the national download to publication share ratio was highest for veterinary sciences (1.81). Downloads of Maryland’s research in veterinary sciences comprised 13.4 percent of all downloads of U.S. research in veterinary sciences. Indicators of citation impact also reflected the strength of Maryland’s research in veterinary sciences; it achieved a field-weighted citation index of 1.93 from 2004-2013, ranked fourth among all states.
Another potential measure of the larger impact of research is how widely that research is read. For example:
A total of 68.4 percent of U.S. research published in 2004–2013 was downloaded by readers from outside the U.S.
Research from Mississippi and Nevada had the highest rates of international readership. 73.5 percent and 73.3 percent of downloads of those states’ research output were by readers from outside the U.S.
In particular, Mississippi and Nevada’s research in biochemistry, genetics and molecular biology had higher rates of international readership (74.2 percent and 70.3 percent) than the U.S. average for that field (64.1 percent).
Figure 4.4— U.S. National Publication Share versus U.S. National Download Share across all States, 2004–13. Source: ScienceDirect® usage
metrics and Scopus®. Trend line indicates publication-to-download share ratio of 1.0.
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