I’m always trying to come to grips with my research productivity or lack thereof. I’ve written about this topic before, but in the interest of having not all of my posts be negative, I decided to take a closer look the current holy grail of non-monetary judgment of scientific research productivity, the h-index. It’s a topic that has recently popped up at a couple places, so what the heck.
The h-index is a fairly recent development in the never-ending search to find out which scientist has the biggest d.., uh, impact on their field. If you have exactly 12 papers that have been cited at least 12 times, your h-index is 12. If you have exactly 100 papers that have been cited at least 100 times, your h-index is 100. Basically, it attempts to balance quantity with “quality”, where quality is measured by how often you papers are cited. With a moment’s thought, one can see that your h-index always increases through your career as you publish more papers and more people cite those papers. Even if you never publish another paper, citations can still pile up and increase the size of your h-index.
I’m sure there’s never been an administrator at my institution other than my department chair that actually knows what the hell the h-index is. There are maybe 3 or 4 faculty who could define it. This is really a game for the people who had the right grad school experience, the right postdoc experience, and a research-intensive faculty position. But, the rest of us can count high enough have some fun with it, too.
A lot of people use Google Scholar searches for this, but it doesn’t do a good job of distinguishing between refereed and non-refereed citations. The latter are fairly worthless in most fields, including mine. Luckily, my field has a field-specific database of papers and citations, so one can do this properly, with good removal of non-refereed publications. Plus, I’ve published few enough papers that I’ve gone ahead and put each one in a spreadsheet, so I can periodically update various other stats I like.
First, I’ve been publishing for about 15 years, starting near the end of grad school. I had no papers from grad school beyond the four first-author (three solo) papers from my dissertation. That’s certainly not normal these days even in my field, and my grad program was rather dissfunctional (ah-ha-ha). I didn’t finish getting those four papers published until two years after graduating. Anyway, I’ve been an author on 27 peer-reviewed papers (plus the one that has just been accepted, but that doesn’t count here). My h-index from these, only using citations in peer reviewed journals, is 17. Only one of the papers from my dissertation counts, and the rest are split between my post-doc years and my current position. The average number of authors on those 27 papers is 8 and the average number of citations is 34.
In my field, first-authorship is the brass ring. I’ve been first author on 8 papers with an h-index of 6. (Remember, the maximum possible h-index is the total number of papers you are considering.) Although it was part of a big group project during my postdoc years, I’m proud of the fact that of my 27 papers, by far the one with the most citations is one where I was first author and did about 90% of the work and was published in one of the top field-specific journals. It has steadily been averaging a bit more than one citation a month for more than 10 years and is still going strong. As of right now, of the nearly 100 articles in that issue of the journal, mine is the third most cited, and just behind number two. (That was actually rather surprising to discover!) A much newer paper of mine on the same topic is getting cited at the same rate even though it’s not as good of a paper, so we’ll see what happens with that one. These two papers bring the average number of citations for my 8 first author papers up to a pretty healthy 39, and that is dominated by the four papers since I graduated.
I know that there are numerous people with h-indices above 100 in several science fields, but haven’t had much luck in figuring out the maximum in mine. One of my most senior collaborators is over 100 and given his age and the projects he’s worked on, he may be fairly close to the top. The top woman I can think of comes in with an h-index of 99, and an impressive score of 37 as first author, higher than my collaborator. My second-most senior collaborator only comes in at 47, which is probably a more normal successful R1-type of career. My dissertation advisor is retired and his h-index is only 23, which tells you something about my grad program. (He was an okay advisor, but really should have moved to a more teaching oriented institution before I started grad school.)
There are some people with very high h-indicies who simply work for major projects and are part of ridiculously large author lists. In some cases, they have fewer first-author papers than I do! To be honest, I didn’t realize that my h-index had skyrocketed up into double-digits. A lot of this is due to the collaboration I’m currently in, as our work slowly gains traction. But, I’m always amazed that a couple of my old papers are still dry-heaving their way up the citation rankings.