# H-Index

Bibliometrics is all about methods used to study texts and information. Much of it, though not all, is about citations, especially as it applies to citation analysis, which we use when looking at journal impact factors (Bandolier 118). Some aspects of bibliometrics have become important for pointy-headed academics because they are used to measure academic worth. Getting papers published in high impact factor journals has become more important than the total number of papers published in some schemes of measurement.

There is now a new kid on the block, and pointy-heads need to sit up and take note. It is the H-index (or Hirsch number [1]), which is much more personal, and is based on the number of citations that each from an author's articles receives. The definition is the following:

*A
scientist has index h if h of his/her Np papers have at least h citations each,
and the other (Np - h) papers have fewer than h citations each.
*

Put simply, a scientist with an index of X has published X papers with at least X citations each. Someone with an H-index of 20 has 20 papers cited more than 20 times each.

### H-index importance

It
is quite easy to find citation numbers, either through the Science Citation
Index, or, more simply, through Google Scholar. A few papers have astronomical
citation numbers (thousands), some have hundreds of citations, more have tens,
and most have just a handful. The H-index is a clever way to establish how much
** impact**
a researcher has had.

### What's good

Nobel prizewinners in physics had H-indices of 20-80. In medicine the index tends to be higher, but the highest is reputed to be about 190. An H-index of about 40-50 should get you admitted to the US Academy of Sciences. An index of 20+ is pretty good for most researchers. Of course there are criticisms of any way of measuring worth, but the H-index is easy to calculate and seems to make immediate sense.

### Reference:

- JE Hirsch. An index to quantify and individual's scientific research output. Proceedings of the National Academy of Sciences 2005 102: 16569-16572.