If one plots a best fit curve of the data (using whatever regression model they desire), along with upper and lower limits of margin for error, all three curves are decreasing, albeit the funnel width is decreasing with respect to the limits of error, but nevertheless all three curves are decreasing.
Furthermore, the problem with current methods of light-speed measurements (mainly laser) is that both wavelengths [W] and frequency [F] are measured to give c as the equation reads [c = FW]. If one is intimately familiar with Setterfield's conjecture, one should be aware that, within a quantum interval, wavelengths are invariant with any change in c. This means that it is the frequency of light that varies lock-step with c. Unfortunately, atomic frequencies also vary lock-step with c, so that when laser frequencies are measured with atomic clocks no difference will be found.
The way out of this is to use some experimental method where this problem can be avoided. Ron Samec has suggested that the Roemer method could be used. This method uses eclipse times of Jupiter's inner satellite Io. Indeed it has been investigated by Eugene Chaffin. Although many things can be said about his investigation (and they may be appropriate at a later date), there are a couple of outstanding problems which confronts all investigators using that method. Chaffin pointed out that perturbations by Saturn, and resonance between Io, Europa, and Ganymede are definitely affecting the result, and a large number of parameters therefore need investigation. Even after that has been done, there remains inherent within the observations themselves a standard deviation ranging from about 30 to 40 seconds. This means the results will have an intrinsic error of up to 24,000 km/s. Upon reflection, all that can be said is that this method is too inaccurate to give anything more than a ball-park figure for c, which Roemer to his credit did, despite the opposition. It therefore seems unwise to dismiss the cDK proposition on the basis of one of the least precise methods of c measurement as the notice proposes that was brought to our attention by Ron. This leaves a variety of other methods to investigate.
However, that is not the only way of determining what is happening to c. There are a number of other physical constants which are c-dependent that overcome the problem with the use of atomic clocks. One of these is quantised Hall Resistance now called the von Klitzing constant. Another might be the gyromagnetic ratio. A further method is to compare dynamical intervals (for example, using Lunar radar or laser ranging) with atomic intervals.
The design of the experiments and the accuracy of the equipment have changed drastically since Roemer's first observations.
If one plots a best fit curve of the data (using whatever regression model they desire), along with upper and lower limits of margin for error, all three curves are decreasing, albeit the funnel width is decreasing with respect to the limits of error, but nevertheless all three curves are decreasing.
Not true, which they tacitly acknowledged when they went to an oscillating model.
Furthermore, the problem with current methods of light-speed measurements (mainly laser) is that both wavelengths [W] and frequency [F] are measured to give c as the equation reads [c = FW].
I don't think so. As I understand it, the propagation time of a signal through some long light path is measured directly or indirectly. Perhaps you are confused because some techniques (Michelson and Morley's, e.g.) involve detecting tiny lags in time by detecting interference fringes in out-of-phase waves.
Unfortunately, atomic frequencies also vary lock-step with c, so that when laser frequencies are measured with atomic clocks no difference will be found.
I assume Setterfield was trying to make his theory as unfalsifiable as possible when he went for that point. But it kills him on having the early earth (say Day 6 of Creation Week) habitable for humans with the sun and earth cooking off like crazy. He tries to dodge that problem, but I don't think he's ever succeeded.
The way out of this is to use some experimental method where this problem can be avoided. Ron Samec has suggested that the Roemer method could be used. This method uses eclipse times of Jupiter's inner satellite Io. Indeed it has been investigated by Eugene Chaffin. Although many things can be said about his investigation (and they may be appropriate at a later date), there are a couple of outstanding problems which confronts all investigators using that method. Chaffin pointed out that perturbations by Saturn, and resonance between Io, Europa, and Ganymede are definitely affecting the result, and a large number of parameters therefore need investigation.
When I first read about this I practically fell on the floor laughing. Roemer's original high reading for c is one of Setterfield's props for his theory, but now the technique is too error-prone to be worth replicating.
All the early measurements were necessarily low-tech. And all the really accurate clocks are atomic. Making your theory unfalsifiable isn't really such a good strategy.