For example, when there is a cluster of cancers at an industrial site, do the investigators say that cancer is common among a percentage of the population or do they say that while common, it's uncommon to have so many cases with the same one thing in common.
The commonality might be a toxic workplace where chemicals were previously stored, or it might be taking the vaccine.
Sure, it might be a comorbidity, but we're talking about young people. I don't know the statistics, but what conditions do you think might be present amongst young men and women that might make these cases not seem clustered around a commonality like all having taken the vaccine?
-PJ
Yes. Cluster analysis is a valuable tool for this sort of big data.