Calling it a contest is a conceit, but my intent is serious. Should the grind setting alone be changed and the dose be kept the same? Or vice versa? Or may split the difference with a small changes to both dose and grind? There is no "natural" answer. If the taster picks a shot profile they enjoy using one alternative, say single dosed; the shot puller should look at dose change only, grind setting change only, or something in between to see which seems closest in taste. This seems less controversial than picking how to go between grinder configurations.

However, it may be best if you stay with the protocol of predetermined doses and settings. I've had some emails on this, and may be able to put together a replication test in the contest format. We would only have one of each grinder, so we'd have to grind single dose, then hopper, then single dose again and combine the two single dose grinds, so that the grind aging factor is physically controlled. I don't know if such a staling control will be perfect, but it's probably better than nothing. We'll also reverse the grinding order in each round as a design control.

I think this goes back to being careful about being clear what you're testing. To me, if you want to flat out know what the effect of single dosing is (heh, at least for a specific grinder), you take every step you can control every variable but that one. It seems natural to me. And it also seems like a natural "first step" in testing, but that's surely much more debatable. It strikes me that when you get into a more practical issue like, can single dosing be tuned to suppress or eliminate the potential differences observed with all variables held as constant as possible, then you're getting into territory where a contest of sorts is warranted. There may be some baby steps in between if you want, but I think again, as John said, there are so many ways to run a test, practically any reasonable format would garner interesting data to crunch and end up being of some use.

So... I am seriously looking forward to what you find if you take up your proposed method.

It is hard to keep up with all of the interesting work you guys do so excuse me if this has been covered - I wanted to pass along these questions to consider:

1) Has the difference in the grind between single dosing and full-hopper dosing been quantifiably established? E.g., have laser diffraction measurements been done to quantify how the particle size distribution changes? This would be very helpful to understand in order to develop a good hypothesis.

2) If laser diffraction does show a difference, is the single-dose grind distribution identical to a simple change in the level of the grind or does it show more complex difference?

3) In a more broad question (stemming from the 20 pages of TGP that I slogged through), has anyone assembled comprehensive but concise summary of the many grinder-related measurements that have been done? I'm thinking of something along the lines of supporting documentation for the "collective knowledge base" that many here seem to work from. As an aside, is more basic work needed? For example, in the TGP there were laser diffraction measurements made for several griniders at one point and extraction studies made for others at another time (and probably with different beans). As interesting as these measurements were, a more complete set of measurements (using the same beans at the same time) for each grinder at several grinder settings would be so much more interesting and insightful. E.g., in the TGP, I recall extraction measurements for the Robur being very flat versus dose. Does this hold for all grind settings? How does grind affect the slope of the extraction vs dose curve of a given grinder? How does the particle size distribution change for the different dose/extraction points? Correlations of these measured quantities with subjective (e.g. taste) impressions would also be valuable.

Good questions.

The laser measures haven't been made on the hopper/no hopper alternatives; maybe this summer.

The extraction measures were done only on the officially tested grinders, not on the complete cast of the "beat the Robur" show. Previous measures on smaller home grinders indicated a very steep drop off in extracted solids as dose was raised, so much so that the taste of higher dose shots was compromised by being underextracted. This was untrue with the larger grinders, which, as you noted, have nearly flat extraction curves. Once most of the HB discussions moved to these higher end grinders, the solids extraction measures became sort of moot.

Those following this thread will also want to read the results of Single dose versus hopper grinding: an experiment.