So your email signature contains your h-index, your Eigenfactor score and the impact factors of the most prestigious journals you have published in. But wait ¨C you¡¯ve forgotten your ¡°t factor¡±.

This is a new Twitter-based ¡°altmetric¡± proposed in a paper, , posted on the arXiv preprint server by two researchers from Germany¡¯s Max Planck Society.

The authors liken a retweet to a citation in that it reflects the ¡°impact¡± of the initial tweet. Hence, based on the formula for the citation-focused h-index, they say that an individual (or paper, journal or research group) should be assigned a t factor of x if they have x tweets that have been retweeted at least x times.

They say the measure is an improvement on existing Twitter metrics, which do not distinguish between tweets and retweets and can be skewed by large numbers of retweets for a single tweet.

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One of the paper¡¯s authors, Lutz Bornmann, a sociologist of science at the Max Planck Society¡¯s Division for Science and Innovation Studies, admitted that it was unclear what Twitter impact actually measured because research showed that it did not correlate with citations. However it may, he suggested, measure ¡°impact on parts of society outside science¡±.

James Wilsdon, professor of science and democracy at the University of Sussex and chair of a recent independent review of the role of research metrics, worried that the t factor ¡°seems highly susceptible to gaming of various kinds¡±.

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¡°It also reflects a rather narrow view of how and why [academics] use Twitter,¡± he added. ¡°Publicising their own papers is a tiny slice of what they tweet about¡­It would be a great shame if an online space that is typically characterised by openness, plurality and a certain playfulness were to be stifled and impoverished by a hasty move to measure and value certain types of activity over others.¡±

David Colquhoun, emeritus professor of pharmacology at University College London and a critic of metrics, said that it was rare to see ¡°a serious bit of basic research¡± mentioned on Twitter.

¡°The best way to get lots of retweets is to write something that¡¯s disastrously wrong or just nonsense. Preferably, it should mention diet or memory or sex or quackery in the title,¡± he said.

¡°If anyone were sufficiently foolish to take seriously the t factor, or altmetrics in general, as a method of assessing the worth of a person or a paper, the result would be corruption of science. The only people to gain would be the commercial suppliers of naive numbers to naive bean counters.¡±

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?paul.jump@tesglobal.com