Assumptions baked into the VMS carbon dating

[Jorge_Stolfi]

The most likely range for the creation of the set of folios that have been tested is ~1404-1435. Other possibilities are considerably less likely. If the parchment was produced over the course of 50+ years, it appears a very strange coincidence that all tested folios cluster in the range that maps both to the peak of ~1340 and to the upslope of ~1420 and none of them appear in the trove of ~1375 where they would immediately stand out and it would be a certainty that the parchment was not all from the same period.

Let's assume that each section of the VMS was written on vellum made from animals that were slaughtered over a span of a few years.  (This already is not a trivial assumption, given the many ways that the vellum could have been procured.  But let's adopt it as working hypothesis.)

With that assumption and the C14  results, we then could say that 

• the Herbal bifolios (3 sampled) were almost certainly (more than 80%) made sometime in 1390-1460. 
  
• the Astro/Cosmo bifolios (1 sampled) could have been made in 1308-1362 (~40%) or 1385-1436 (~50%).
  

And we could not say anything about any of the other sections. 

On the other hand, suppose instead that a random subset of 5 of the 50(?) bifolios were made in ~1500, while the other 45 were all made in ~1425, which is compatible with the measurements.  The probability that a sample of four bifolios would miss all those 5 anomalous ones is (1 - 5/50)^4 = ~65%.   But even a single bifolio from ~1500 would push the probable date of the writing to post-1500...

All the best, --stolfi