"The Currier languages revisited" revisited

[kckluge]

Very interesting and comprehensible analysis, thank you. Quire 8 pages misbehaving comes as no surprise.

I wonder if the cloud of Zodiac pages can be seen as somewhat bridging the gap? Maybe it behaves differently because it's purely circular text?
Likely, which pages of Pharma and Stars are part of the Herbal A cloud? Might this also have something to do with the ratio of paragraph text vs. labels/circular text?

If only running paragraph text is used with the same 40 bigrams, the results are similar with a couple caveats: f70r2 is the only Zodiac page in the sample; several of the Astro/Cosmicological pages drop out due to lack of running paragraph text; and the text sample sizes on the diagram pages get smaller (and therefore noisier from a variance perspective). Here these two axes capture a hair over 50% of the overall covariance:

   

The f58 & f65 pages still fall in the B cluster (unsurprisingly). The lone Zodiac page is on the border between the A & B clusters, and one of the Rose foldout pages drifts towards the big Pharma group, but that's as likely to be due to the smaller text sample on those pages after circular text is excluded as anything else.

With respect to the relationship between the Herbal A, Pharma, Zodiac, and Astro (circular diagram) pages, using the same 40 bigrams on running paragraph and circular text but doing PCA on just those data points yields the following plot (first two dimensions capture ~43.5% of the total covariance of that set of points):

   

While there is some overlap, it looks like the zodiac & circular diagram pages are in a different "dialect" than the pharma & pharma-adjacent herbal pages. That's why it's so important to be careful about interpreting lower dimensional projections -- they look like they fall on top of each other when you use the first two axes returned by PCA over all the pages, but that's an artifact of PCA being forced to find directions that capture the main A/B split.

Doing the same thing for the B language pages (the first two axes here capture ~48.3% of the B page covariance), the Bio pages fall in a group towards the upper right; the Herbal B pages (albeit with a few stragglers), the Rose foldout panels, and a chunk of the Starred paragraph pages fall in a group towards center left, and a chunk of the Starred paragraph pages fall in between the two (presumably reflecting the split between Starred paragraph pages Rene found on the basis of differences in most common word vocabulary -- You are not allowed to view links. Register or Login to view.):

   

The same caveat about caution interpreting overlaps in a lower dimensional projection apply -- pairwise comparisons of Herbal B, Bio, Rose foldout, and Starred paragraph sets of pages would probably give a more reliable sense of the substructure in the B language "dialects".

With respect to "if the cloud of Zodiac pages can be seen as somewhat bridging the gap", the point of the analysis was to test (and push back on in a data driven way) the whole notion that there is some smooth gradual transition between the A language pages and the B language pages. That's just not what the relative bigram frequency data appears to be saying. While they are probably (almost certainly) instances of some common underlying scheme, they appear to reflect separate discrete versions of that scheme.

An interesting question is what the PCA plots would look like if tested on the 40 most common bigrams in comparably sized "pages" of mixed (say) English, French, and Spanish. I suspect the scatter within a given language would be lower and rather more Gaussian looking than the results for the Voynich pages.