Like with any scientific research you need more participants in the study to produce significant results.
(The EMS studies I participated in were awesome.)
I’ll check it out. Simplest, most straight forward solution so far. Far from exact, and not suitiable for more than giving a pointer. But that might be enough for this purpose.
The test/review is not primarily a technical one. The technical part of it is just to add a little bit of objectiveness into it.
Geez, I would of thought is thread would be more lively. 
I think Firelight2 is on the right track. Although the amplitude of vibration might not be enough to cause cavitation resulting in bubbles, I believe there would be some ripples created on the surface of the water. An eyeball estimate of the amplitude (size) of the ripples might be useful, as might side-by-side videos of two different tests.
Another liquid suggestion; start with fresh water in a clear glass vessel. Place a device in the water & allow any resulting agitation to dissipate for, say, 10 minutes to make sure the liquid is still. Place one drop of food coloring a specified distance from the device. Apply power, and time how long it takes for the food coloring to be evenly dispersed in the tank.
For AC powered devices, the wattage draw of each device may be useful for power estimates.
slmjim
Don’t mind me, just sitting here wondering if there are any designed for 240v outlets… 
There are 
Meh... lightweight.
A real vibe is kickstarted.
slmjim
use a stopwatch
measure how fast your fiance gets off.
post a video
accelerometer on the device, record waveform, calculate RMS value of output waveform in all 3 dimensions
suspend it from a string, i guess
either that, and/or hold it in a vise
ignoring the subjective ‘lady response’ factor
this sounds so nerdy that probably anyone doing it, probably has no lady to do it with…
amirite!
?
You could measure the time a vibrator needs to turn a defined amount of fresh cream into whipped cream that is solid enough to hold a marble.
But you MUST make a video of this surreal scene of the test row.
I've followed your suggestions in the thread with joy and interest. Thank you so much for all input!
I can't think of anywhere else, where I could hope to get even half serious answers :) .
Now, based on your suggestions, I've been thinking.
How about this:
-Mount some kind of suitable, known weight on the tip of the vibrator, which usually is the part that moves the most.
This should simulate the pressure the user uses against her or his genitalia, with a standardized value.
=WEIGHT(mass) that moves
-Use a camera to measure the movement of the mounted weight.
(Would have a scale in the background, and look at the edges of the "cloud" that is drawn in the picture).
=DISTANCE moved
-Use a sound analyzer to measure the actual vibrating frequency.
This eliminates the need of a vibration sensor and should be accurate enough?
=FREQUENCY
Shouldn't these values, together,
give an approximation of each vibrators power relative to each other?
I don't know what the formula should look like though.
Frequency * moving distance * weight?
I could always say, use an “Ohhhh!”-meter.
(“Ohmmeter”, in case that doesn’t land.)
I’m not sure using a sound analyzer is the best way to go. Noise from the motor might be louder on some samples due to choice of motor or insulating material. Noise alone may not actually translate to stronger vibrations.
Though I suppose it could help you measure the frequency of vibrations.
Somehow related:
