Eugene Garfield died Feb. 26th. Ever heard of him? No? And yet, he has had a huge influence on how scientists work today. Garfield is the person who brought to life the Science Citation Index, which you may know as the Web of Science. This has allowed us to efficiently search the literature forward in time, and has also spawned a cottage industry in trying to measure the impact of scientific studies, of the journals they were published in, and of the scientists who carried them out. One way or another, if you’re a scientist, Garfield has changed your career.

Garfield started out as a chemist, but by his own account, he wasn’t very good at it. One thing led to another, and he ended up creating a citation index for science. You can read the story elsewhere. It’s interesting, but I want to talk about his impact on science and scientists.

The practical impact of the Science Citation Index and of its modern descendant, the Web of Science, has been enormous. Have you found a key paper in your field? By doing a citation search, you can find out how people followed up the original idea. If you’re not already doing citation searches regularly to find relevant material in the literature, you are living in a state of sin. If you don’t know how, run to your university library, and ask a friendly librarian to show you. This is an indispensable skill for a scientist, and one that you can learn in just a few minutes.

Once we had a citation index, it became easy to count the number of citations a paper, or a scientist’s total output, was getting. And eventually some bright spark decided that counting citations was a good way of deciding how important a scientist’s work is. Citation counting is a tricky business because citation rates are affected by a whole host of non-scientific factors, including different cultures in different disciplines. Still, used wisely, citation statistics can help round out the picture when trying to assess a scientist’s work, especially if we allow a paper to mature a bit before we start counting.

At some point, Garfield hit on the idea of trying to use citation data to measure the impact of journals, and thus was born the Journal Impact Factor. The Impact Factor is the number of citations to articles in a journal from a two-year window divided by the number of articles published in that period, so it’s essentially an average number of citations per article in a very narrow window of recent time. Although the impact factor was intended mostly as a tool for librarians to use in allocating resources, it has been widely abused as a proxy for journal quality. If you ever apply for a grant, someone is bound to look at the impact factors of the journals you have published in to try to assess how important your work is. Yes, that’s right, if you get into the right journal, you can bask in reflected glory. On the other hand, if you publish in a journal with a small impact factor or, heaven forbid!, a journal that isn’t indexed in the Web of Science and that therefore doesn’t have an impact factor, then you really have to track other measures of quality carefully because people will automatically assume the work is of lesser quality. Garfield hated this way of using impact factors, but sometimes you just can’t control the monster you created.

So whether you’re searching the literature or applying for money, you’re living in Eugene Garfield’s rather large shadow. A giant has passed. We owe him a great debt. If you want to honor his legacy, use citation searches and teach them to others, and try to make sensible use of citation statistics and impact factors.