sh_ and ch_ compose the same words

[ReneZ]

Picking up on this message:

I did not yet list the percentages of chedy and Shedy occurences for the different sections.
They are:

              chedy   shedy
              -----   -----
Herbal B:     1.933   1.132
Biological:   2.979   3.485
Cosmo:        1.155   0.880
Stars (all):  1.732   1.048
Stars-Bio:    1.984   1.297
Stars (rest): 1.355   0.677

Total:        2.092   1.780

This shows that there is a general trend, but still significant variability between the different sections.
It is mainly in the Biological section that there is also an internal correlation.
I wonder if this could be related to the hypothesis that this quire is a mixture of two original quires. There has been quite some speculation about that

Looking back at the information at Ciphermysteries, the proposed split of Q13 is:
Q13A : fol 76+83 , 77+82 , 79+80
Q13B : fol 75+84 , 78+81
This is a split of bifolios into two groups based mainly on the illustrations. Q13A is presumed to be the 'earlier' one since it starts with a text-only page.

This leaves only 12 'observations' for Q13A and 8 for Q13B.
Computing the statistics using nablator's approach shows correlations of:
+0.718 for Q13A
+0.463 for Q13B
Is this significant? If so, it is certainly only marginal, but it would be interesting to see how a selection based on the illustrations shows up in the text.
What is mostly visible is that the variation in fractions of Shedy per page is similar in both parts, while the variation of chedy is much less in Q13B. The ratios of Shedy / chedy for the two parts are:

1.11 for Q13A
1.29 for Q13B

Again this seems rather marginal.