the tests are administered to certain “ at-risk “ groups. You didn’t take your Sherlock hat off, did you?
I’m wearing my two-semesters-of-stats hat, the one with the big white silk peony on it. The “percentage of at-risk newborns screened” does not tell us “at-risk newborns as a percentage of total births.”
Suppose 100 babies are born. Suppose ten percent of them are at risk of sickle-cell disease. Six of those are screened. The percentage of at-risk newborns screened is 60%. This chart (if I read the caption correctly), gives us that final number. It does not give us the middle figure, the percentage of the whole that is at risk.
The numbers by region are consistent with a measure of screening accessibility: high in the Paris area, low in rural Brittany.