Comment by gpderetta

Figure 2 is now Figures S2 and S3 in the newer paper. Table S1 is also relevant: all four Sardinian provinces that appear in that table have existed only from 2005 to 2016. The other 4 historical provinces do not appear. I can't help but think that they didn't somehow account for that and it messed up their data.

Although the fact that those four provinces stick out as extreme outliers in their graph should have clued them that something was wrong.