I don’t wish to under-estimate the difficulties. I am well aware of the risks involved, particularly to young researchers trying to forge a career in a culture that is so inured to the impact factor. It will take a determined and concerted effort from those in a position of influence, not least by senior researchers, funders and university administrators. It won’t be easy and it won’t be quick. Two decades of criticism have done little to break the addiction to a measure of worth that is statistically worthless.

But every little helps, so, taking my cue from society’s assault on another disease-laden dependency, it is time to stigmatise impact factors the way that cigarettes have been. It is time to start a smear campaign so that nobody will look at them without thinking of their ill effects, so that nobody will mention them uncritically without feeling a prick of shame.

So consider all that we know of impact factors and think on this: if you use impact factors you are statistically illiterate.

• If you include journal impact factors in the list of publications in your cv, you are statistically illiterate.
• If you are judging grant or promotion applications and find yourself scanning the applicant’s publications, checking off the impact factors, you are statistically illiterate.
• If you publish a journal that trumpets its impact factor in adverts or emails, you are statistically illiterate. (If you trumpet that impact factor to three decimal places, there is little hope for you.)

If you see someone else using impact factors and make no attempt at correction, you connive at statistical illiteracy.