Thank you, Donald! I think the PCA diagrams provide a useful tool to compare different scripts.
You write that the diagrams can be "rotated or reflected" and mean the same: I guess that a 90 degrees rotation would swap the first and second components, and I am not sure that would be desirable. For instance, in Italian it is the X axis (1st component, I guess) that separates vowels from consonants. But mirroring one or both axis so that the most frequent letter (excluding *) is in a fixed quadrant (e.g. bottom-right) could help the visual comparison.
In your analysis, your write that some of the plots "vaguely resemble the Voynichese plot". It would be great to have a quantitative similarity measure as an indicator of how much two plots are close or different.
You write that the diagrams can be "rotated or reflected" and mean the same: I guess that a 90 degrees rotation would swap the first and second components, and I am not sure that would be desirable. For instance, in Italian it is the X axis (1st component, I guess) that separates vowels from consonants. But mirroring one or both axis so that the most frequent letter (excluding *) is in a fixed quadrant (e.g. bottom-right) could help the visual comparison.
In your analysis, your write that some of the plots "vaguely resemble the Voynichese plot". It would be great to have a quantitative similarity measure as an indicator of how much two plots are close or different.