How the Top 2% c-score is calculated (formula, example and calculator)
In short: the c-score adds six citation measures. Each one is turned into ln(1 + your value) ÷ ln(1 + the highest value in the database), which gives a number from 0 to 1, and the six are summed. The c-score therefore runs from 0 to 6, and your rank inside your subfield decides whether you are in the top 2%.
The six measures
NCAll citations to all your papers.Hh papers that each have at least h citations.HmLike the h-index, but a paper with many authors counts as a fraction.NCSOnly papers you wrote alone.NCSFPapers you wrote alone or lead as first author.NCSFLAdds papers where you are the senior (last) author.The formula
Here xi is your value of each measure and max xi is the highest value of that measure among all authors. Two things follow from the log scale:
- Early gains count more. Going from 10 to 100 citations to your solo papers adds as much as going from 1,000 to 10,000. A measure where you are near zero is the cheapest place to gain.
- No single measure can carry you. Each one gives at most 1 point, so a huge citation count with almost nothing as first or last author still leaves three of the six measures low.
A worked example
Take a researcher with 3,000 citations, h-index 25, hm-index 11, 50 citations to solo papers, 700 as single or first author and 1,500 as single, first or last author. With the example maxima below, total citations give 0.64, but solo papers give only 0.36. Writing one well-cited solo review that brings 200 citations would lift that one measure from 0.36 to about 0.50, a gain of 0.14, while doubling total citations to 6,000 would add only 0.06.
Try it with your numbers
The highest values here are round examples so the calculator works; the real ones come with each edition of the list. Use it to see which measure moves your score most, not as your official score.
Why your Google Scholar numbers will not match
The list works from a citation database that indexes fewer sources than Google Scholar, so your citations and h-index there are usually lower, sometimes much lower. Comparing your Scholar numbers directly with the list’s cut-off makes you look closer than you are. The Top 2% Standing Check adjusts for this before comparing.
Questions people ask
How is the Top 2% c-score calculated?
Each of six measures (total citations, h-index, co-authorship adjusted hm-index, citations to single-author papers, to single or first author papers, and to single, first or last author papers) is turned into ln(1 + value), divided by ln(1 + the highest value of that measure in the whole database), and the six results are added. The c-score therefore runs from 0 to 6.
Why does my Google Scholar citation count not match the list?
The list uses a different citation database, which indexes fewer sources than Google Scholar, so citation counts and h-index there are usually lower. Compare yourself with the list only with numbers worked out the same way.
Which part of the c-score is easiest to improve?
For most researchers it is the three authorship measures: citations to papers they wrote alone, as first author or as last author. Many productive researchers are middle authors on most of their papers, and those citations do not count there.
More on the Top 2% list
Your own numbers against the Top 2% of your subfield. The free check opens soon.
See the Top 2% Standing Check