Nice find Kirk! Sure I'll go in on it, but can we keep it at my house?
Of course, testing one's materials is a good idea. The question has to be asked about how valid the tests are. Is a "standard" light bulb going to be consistent enough to produce accurate results? Is the tester considering all of the variables that could influence the result? Take a look at any testing equipment and most of it is to insure accuracy and repeatability. There are feedback systems and regulators that makes something as simple as using a photo detector to read the density of a piece of film into a pricey option. And if you want that to be really accurate, then the price shoots up astronomically. Just ask P.E. about the difference between a commercial densitometer that reads 0.00 with an +- 0.01 error with what Kodak uses.
Part of the precision comes from confirmation of that precision. My sensitometer is designed to give repeatable and knowable exposures, but it has to be calibrated to confirm what those exposure values are, and the device that calibrates the sensitometer has to be calibrated too, and so on. The "standard" bulb may have a particular illuminance that is common for that bulb in general, but what about specifically. How can you verify the actual output of the bulb? Variations in manufacturing occur. Somewhat ironic when you are using it to calibrate the one thing that might be able to verify it. Home voltages vary. How accurate is the voltage regulator and is that accuracy knowable and provable? Potential errors can build up quickly.
Then there's actually doing the tests correctly. Take one of my favorite subjects for ranting, Zone System speed testing. The reason why people tend to produce personal speeds lower than the ISO speeds in a consistent manor is because of a false assumption in the test. And that's not including the question of precision of changing the f/stops in increments of 1/3 stop, or the color temperature of the light source the test was made of, or a number of other potentially influential factors. How many consider the concept of hold time? Most also only do the test once thus making it impossible to determine if that one test is an outlier because of procedural errors. Yet, somehow, many of these people point the finger at the manufacturers as being incorrect with speed testing.
I would estimate that around 95% of those who have read the ISO film speed standard are probably misinterpreting a central tenet which has to do with a fixed density to determine film speed. One of the few disagreements I have with Phil Davis has to do with this one point. I believe he was aware but decided not to deal with the issue in BTZS. Even with all this error, most people still manage to produce good images.
With most amateur testing, are we actually doing it to achieve a better understanding of the materials, or are we really doing it to predicate a false sense of control and understanding?