>If there's a dense line in there, how come it's not sticking out of the blob even a little? It is. If you look at the density in the upper right of the cloud,

>If there's a dense line in there, how come it's not sticking out of the blob even a little? It is. If you look at the density in the upper right of the cloud, it is clearly clustered around the x=y line. The correlation may not be very strong, but without extra information about how strong of an effect would constitute clear evidence in favor of including the value add metric, we can't say anything more about it. > Do actual phenomena often yield "deceptive" blobby scatterplots with dense lines hidden inside them? Absolutely. You're looking at a misapplication of a plotting technique - a scatterplot with substantial overplotting. The author may be convinced that there's no correlation there, but by presenting this plot they provide no evidence in support of their point.