pjburkshire > Today, 09:45 AM
DG97EEB > Today, 09:50 AM
(Today, 09:45 AM)pjburkshire Wrote: You are not allowed to view links. Register or Login to view.Novels have reading order. I don't think of reference books as having a reading order. Most people don't sit down and read a cookbook. They go directly to the page with the topic of interest.
Rafal > Today, 11:52 AM
npcompl33t > 8 hours ago
(Today, 08:36 AM)MarcoP Wrote: You are not allowed to view links. Register or Login to view.Thank you very much for this thread! As far as I know, Guttman and Kendall were never mentioned in the context of Voynich studies. It’s great to know that Rene’s findings fit into a pattern that also shows up in the archeological data of Flinders Petrie.
I have always been puzzled by that V-shape of PCA1 vs PCA2, but I think I can now partially understand why this happens.
A detail I am not sure about is that the first plot in post #1 shows Biological as the extreme B-side subset, while the last post shows part of Stars as the extreme. I guess this depends on the shape of the green line in the second plot (MDS1, MDS2): that green curve seems to me to be a little weird at both extremes, so I am not fully convinced of the stars-bio-stars chronology.
Jorge_Stolfi > 6 hours ago
(Today, 02:53 AM)npcompl33t Wrote: You are not allowed to view links. Register or Login to view.This is what is known as a Guttman horseshoe. It is a You are not allowed to view links. Register or Login to view. You are not allowed to view links. Register or Login to view.that can happen with both PCA and MDS.
npcompl33t > 5 hours ago
(6 hours ago)Jorge_Stolfi Wrote: You are not allowed to view links. Register or Login to view.(Today, 02:53 AM)npcompl33t Wrote: You are not allowed to view links. Register or Login to view.This is what is known as a Guttman horseshoe. It is a You are not allowed to view links. Register or Login to view. You are not allowed to view links. Register or Login to view.that can happen with both PCA and MDS.
This "Guttman effect" is a fancy name for the banal observation that, if you try to fit a simple arc of curve to a bunch of random points in 2 or more dimensions, the result will usually be a curved arc rather than a straight line.
There is no reason to assume that the different sections of the VMS were created by a single process (natural or mechanic) whose parameters varied gradually along a single dimension (like time). Therefore, there is no justification for trying to fit a single curve to the clouds of points obtained from each section. They are expected to have different statistics because of different subjects, formats, and styles.
If cloud B happens to lie somewhat between clouds A and C in a particular projection, it does not follow that it was created after A and before C,or vice-versa. It does not even follow that its topic is somehow "intermediate" between those of A and C.
All the best, --stolfi
RadioFM > 4 hours ago
npcompl33t > 3 hours ago
(4 hours ago)RadioFM Wrote: You are not allowed to view links. Register or Login to view.I think this result was to be expected. Let's see if I'm getting this right:
The horseshoe curve is IMO the algorithm trying to keep the triangle inequality in the N-space (not of J-S Divergence but of the matrix norm in the MDS), telling you: "Hey, Pharma is different than Herbal A and Bio / Stars, but it's not exactly a smooth segway all N=230 pairwise Jensen-Shannon Divergence distances considered, you know?"
I'm not entirely getting the "polynomial correction" step. You can flatten any polynomic function into a line by compositing it with another function afterwards. Are you basically interpolating the 3rd PC dimension with a 4 degree polynomial and then mapping/flattening that to a line? Because in that case I'd argue that'd be skewing the data just to fit a line, not particularly insightful
Your results don't look wrong, btw -- on the contrary, they're are consistent with René's, MarcoP's, Torsten's and others'. I just think you're basically retreading the same path, except for the line fit step, which I'm not quite understanding what you did
Jorge_Stolfi > 1 hour ago
(5 hours ago)npcompl33t Wrote: You are not allowed to view links. Register or Login to view.Sorry, I was referring to the "Guttman horseshoe".(6 hours ago)Jorge_Stolfi Wrote: You are not allowed to view links. Register or Login to view.This "Guttman effect" is a fancy name for the banal observation that, if you try to fit a simple arc of curve to a bunch of random points in 2 or more dimensions, the result will usually be a curved arc rather than a straight line.
Respectfully, this statement is not accurate. The Guttman effect by definition can only occur when a strong, single underlying linear gradient or sequential ordering is forced into a lower-dimensional space using linear dimension reduction techniques.
Quote:Its very appearance does in fact mean there is some single underlying linear gradient in the data. You can argue that gradient does not represent time, but you can't claim that such a gradient does not exist. It very clearly does, and is a prequisite for the horseshoe shape to appear.I still take issue to that.