sh_ and ch_ compose the same words

[ReneZ]

I also get exactly the same correlation ( +0.5714 ) for the percentages of chedy and Shedy per page.

Here is the colour-coded plot for these percentages:

   

The correlations for these groups are:

Herbal:    0.3275
Biolog.:    0.6301
Cosmol.: -0.0642
Stars:       0.1469

These are largely the same values as found for the differences, according to the definition of @nablator