If you want to work from published specs, you should find this
interesting, from the Belden catalog:

It looks like 8214 and 9913F7 are the same except that 9913F7 has a
solid aluminum shield between the insulation and the braided copper
shield. 9913F7 claims lower loss, amounting to 0.9 dB at 400 MHz. One
might conclude that the difference is due to the extra shield,
presumably because it's smooth and not braided.

It looks like 9914 is the same as 9913F7 except that 9914 has a solid
rather than stranded center conductor. The spec for 9914 shows less
loss, amounting to 0.4 dB less at 400 MHz. One might conclude that the
difference is due to stranded vs. solid center conductor.

I think your analysis isn't valid for two reasons. The first is that
you're relying on published specifications. (For example, I just
measured the Z0 of ten "50 ohm" cables of different brands and types I
have on hand -- it ranged from 44.6 to 56.8 ohms. I already reported a
loss measurement that was quite different from the spec.) The second is
that your model is overly simplified. It looks like you're trying to
account for all the loss mechanisms in a coax cable by considering only
the dielectric and conductor losses in idealized materials, or at best
two factors which are proportional to F and proportional to the square
root of F. In order to get a decent fit, I think you'll have to include
additional factors for such things as the effect of stranding the center
conductor and the extra loss associated with a braided shield, which
might well be different functions of frequency. Of course, tinned
conductors, which are very common, will alter the loss characteristics
depending on the composition of the plating, and change the shape of the
loss vs. frequency curve at a frequency depending on the depth of the
plating. Once you start really digging, I think you'll find other
mechanisms, such as perhaps how tight a woven shield is -- it wouldn't
take much of an air gap between the shield and the insulation to have
some pretty noticeable effects.

I went through this excercise of attempting to predict coax cable loss
many years ago (my notes say 1991) and abandoned the effort as being too
time consuming. I hope you'll be willing to devote the time and effort
necessary to come up with a reasonably accurate model.

Roy Lewallen, W7EL