RE: Increases in COVID-19 are unrelated to levels of vaccination across 68 countries and 2947 counties in the United States - European Journal of Epediemiology
I didn't know what impact factor was, and I didn't feel like taking time to understand the Wikipedia page, so I did a little more research.
Here's what made it clearer for me:
it is a measured frequency that shows us how many times articles from a journal have been cited in a particular year. This allows determining the rank and importance of the journal by calculating the number of times its articles have been cited.
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The impact factor is a subjective matter and has the most meaning only when comparing journals within similar fields. A good example is a journal in physics where a score of 2 is often considered excellent, meanwhile, experimental material sciences have a great number of pieces rated over 10.
One interesting aside is that apparently the metric was initial created to guide purchase decisions by librarians (i.e. indicating the most read journals).
I found a chart, which seems out of date, but I think gives a valid general indication of what this journal's impact factor might mean in appropriate context: 7+ is very high.
Even though it seems low compared to the 38 for Nature, and one of American Cancer Society's journals—which landed a 435.4!—this journal scores in quite a high percentile in its discipline.
I checked this because - when I know nothing else about a journal - it gives me a crude estimate of the article's credibility. It can be argued that it's more about popularity than quality, but at least it's something.
And yeah, consistent with your chart, when I saw that it scored higher PlosOne, that suggested to me that it has achieved some minimum level of reputability.
I never knew of it, so thanks for including it!