Thread by @dnepo

So this is an example of how Impact Factor may not always tell the full story.

Reminder - 2021 impact factor is calculated as:

Denominator: articles published in 2018-19

Numerator: citations to those denominator articles, published in 2019-21

So what's happened at IJS?

https://twitter.com/HerniaResearch/status/1410341063018024970

In the IJS impact factor calculation, two articles in the denominator account for 37.5% (1342/3582) of all citations.

No other articles captured in the denominator received >25 citations.

Excluding those top two articles would drop IJS IF from 6.1 to 3⃣.8⃣ (2240/588).

What's the issue with including those top two articles in IJS impact factor calculation?

Well, take a look citations to the SCARE 2018 Statement.

Web of Science currently lists 1,804 citations for SCARE 2018... of these 97.7% (1762/1804) were from IJS Publishing Group journals

Why does IJS (a small publisher) account for 97.7% of these citations?

Well, IJS policy is that any case report must cite SCARE 2018. So, for example, that means every single article in IJS Case Reports cites SCARE 2018.

Non-IJS Group case report journals don't mandate SCARE.

The SCARE 2018 Update Guideline won't be captured in next year's impact factor as the 2022 impact factor will be based on articles published in 2019-20.

However, a new SCARE 2020 Update Guideline (sciencedirect.com/science/articl…) will be included in next year's impact factor.

I emphasise there is nothing improper - the IJS team developed and implemented a series of reporting guidelines that they hoped would improve the quality of articles published across their suite of journals. That's commendable.

But- it's useful to look at how IF rise came about

Sorry, the denominator should be - citations in articles published in 2020 (including on this occasion both articles with issue year in 2020 or early access in 2020).