More and more scholarly literature is published every year, so it can be a challenge to keep up with the developments in your field, much less the developments in other fields that might be of interest to you. Scholars have always used filters to choose what to read, perhaps preferring certain journals over others or taking the recommendations of colleagues. However, new ways of measuring scholarly output, called “altmetrics,” might provide better ways of picking out the most influential and important new scholarship.
Altmetrics, or “alternative metrics,” are an emerging field of new methods for measuring the use and importance of scholarly articles, particularly in the sciences. As opposed to more traditional bibliometrics, such as Impact Factor, altmetrics provide article-level data and are based on new electronic sources of information, such as number of downloads and page views from a publisher, repository or online reference manager like Mendeley, or the amount of discussion generated in online venues such as Twitter or blogs.
Impact Factor (IF) has been important in assessing the scientific and technical literature ever since it was introduced in 1955. Working from the assumption that citations indicate influence, it measures the number of times that articles in a journal are cited by other journals over a two-year period, divided by the total number of citable items in the journal. It has been used to compare the importance of different journals when considering venues for publication, choosing which journals to read in a crowded publishing environment, or (controversially) as a proxy to judge the importance of an individual scholar’s work.
Although its use is commonplace in the sciences and is integrated into Thomson Reuters’ Web of Knowledge database, its limitations have been the topic of debate. Because it measures citations at the level of the journal, it cannot reliably be used to draw inferences about the impact of a particular article or author. (Critics point out that “typically only 15% of the papers in a journal account for half the total citations. Therefore only this minority of the articles has more than the average number of citations denoted by the journal impact factor.”)
Even when used for the purpose of ranking journals, it has faced criticism on several counts:
Other methods exist for measuring the impact of an article, journal, or author using citations, including ways of measuring how often an article has been cited. However, the fact of citation is not necessarily proof of influence or approval. One report uses statistical methods to claim that 80% of sources in bibliographies are not actually being read by the people who cite them, and citation practices vary widely across disciplines. Other tools attempt to take these complications into account, such as:
Altmetrics make use of the many kinds of data besides citations that can tell us about the importance of articles. Before the internet, the only quantifiable measure of an article or journal’s impact was the number of times it was cited. Today, there are a number of different data sources, from page views, downloads, and comments to the number of mentions on blogs or social media. The ability to combine different kinds of data from multiple sources promises to give a more fine-grained picture of an article’s influence, and to make that picture available much more quickly. Because of the slow pace of academic publishing, it can take months or years before an article begins to show up in journal citations in any number. The relative speed of altmetrics means that they can be useful guides to the current literature, and their association with open access and open source means that the data they generate can be personalized and repurposed.
Altmetrics are still in the experimental phase. There is not yet widespread agreement about how to choose, analyze, and combine sources of data to provide a reliable indicator of influence. Likewise, because they rely on new data sources, it is impossible to use them to make comparisons to the past. Finally, whereas traditional metrics relied on data pulled from the scholarly literature, altmetrics draw on sources like blogs and twitter whose importance is growing but whose role in scholarly communication is still changing and subject to debate.
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