The determination of planets is in three ways: naturally, accidentally and specifically. Their indications and significance is based on these three elements. Their universal or “natural” significations are just that; universal. But that testimony may be (and I can’t lay any percentage on how often) weaker than its accidental or specific testimony just as often as not!
This is why trying to prove anything statistically is futile. Perhaps delineation could be measured but absolutely not with the methods presented so far. A statistical method would have to be able to separate and show clear lines between the differences that occur in delineation and signification. That is a very difficult thing to do since one might arrive at a type of profession, for example, because of the testimony of the lord of the 10th and another with the same type of profession where the indications are because of an angular “natural significator of profession” joined to another. Because there is no “one” and “only” means of delineation, then how do you separate and distinguish significations statistically? In fact something is determined because it has a preponderance of testimony and not just one!
I can show you dozens of examples of real people who have the same type of work (for example I have many charts of architects and engineers), and no two of them are alike in their determinations! But if you consider all the elements that we are reminded by the ancients to use, then we will find that charts are individuals and are each unique but give “similar” indications.
We can find this in Sahl for example. When discussing illness was their just one signification? No… here is a typical example from Sahl Ibn Bishr;
1 Now as for illness, recognize in which sign the Moon is, and in which degree, and who is looking at her from the aspects, and who is partnering with her and associating with her, and especially in the house of illness. 2 Then, see what the Ascendant is and what its nature is, and do not neglect to know the place of illness (and it is the sixth house), what it is and who of the planets is in it, and who is its lord, and know the Lot of illness.
1 Now as for the lords of chronic illness, look at the sixth house and its lord, and the aspect of the infortunes to it. 2 Then, look also at the Lot which is called the Lot of chronic illness, and its lord, and the sign in which they both are, and who of the fortunes and infortunes is looking at them. 3 Then, look at the second lord of the triplicity of the house of fathers, and who of the fortunes and infortunes is looking at it. 4 Then, look at the sign which is the house of chronic illness: over which limb (of the limbs of the body) does it have authority? 5 Then, look at the Lot of Fortune and its lord, and the mixture of that planet and the sign in which it is. 6 Then, look at the separation of the Moon, and her connection. 7 Then, look at the Head of the Dragon: is it with the infortunes or with the fortunes?
With the Ascendant there are 8 significators listed just for illnesses! And that is not counting looking at the Releaser or Giver of life!! This is absolutely typical of pretty much all the houses and accidents happening to a person in life.
This is what irritates many people today who read these ancients texts; one astrologer tells us to look at one thing and another tells us to look at another. Has it ever occurred to anyone that either is valid or is necessary to establish a preponderance of testimony? – And people give up on traditional because one technique does not give a testimony 100% of the time. Instead of trying to cast one rule into stone, we have to know many circumstances and the results of those particular circumstances and weigh them all in each nativity, which is unique in itself and unlike any other.
This is why trying to statistically analyze particular significations is hopeless and waste of time. I stopped trying to justify astrology a long time ago. Because even if I could devise a statistical approach which took consideration of all the factors of “determination” or “disposition“, still the modern scientific mind-set would never accept that I understand something because of “wisdom”. So I’ll let people continue to argue and theorise on the subject. As for me I just continue to practice it, every day and on real live people and their problems and victories.
 On Nativities Chapter 6.1: On illness and ailments (p.538) – The Astrology of Sahl B. Bishr Volume 1 – translated from the Arabic by Benjamin Dykes PhD and published by Cazimi Press 2019
 On Nativities Chapter 6.3: On the lords of chronic illness (p.552) – The Astrology of Sahl B. Bishr Volume 1 – translated from the Arabic by Benjamin Dykes PhD and published by Cazimi Press 2019