The "field" test is feasible, but is more difficult to execute than the "discrete-location" test I describe in my challenge. Let's call my test the "Plate Test" and this 2-acre test the "Field Test".
First, what is a "success"? The recovery of a target? OK, how big of a hole is allowed? A 1-foot diameter hole? A 3-foot hole? A 10-foot hole? This sounds silly, but it needs to be defined. Otherwise, a dowser could legally dig a 2-acre hole, recover the targets, and claim success. That's what I would do, if offered $1 million with no stated limit on the hole size.
Hole size also plays into the odds of finding targets by guessing. In a 2-acre field (87120 sq feet) a 1-foot hole (0.785 sq feet) gives a probability of about 1-in-111,000 for a single target. A 10-foot hole (78.5 sq feet) gives a probability of about 1-in-1110 for a single target. Both of these sound highly unlikely, but when you bury a number of targets then the likelihood of finding one is not as bad for the 10-foot hole, versus the 1-foot hole. So you need to limit the hole size to be very small compared to the field size.
In the plate test, none of this is an issue, because the target is hidden in a discrete, marked location. There is no "get close and get lucky"... you either hit it, or you don't.
Second, the dowser will probably want to pre-scan the field for anomalies. In the Plate Test, I strongly recommend this before the test begins. In the Field Test, this means the dowser will have to check the field, then leave while the targets are buried. Depending on the surrounding area, you would need to exercise extreme caution to prevent observation, because it's difficult to disguise the digging of a hole. In the Plate Test, I can easily conceal the target with no fear that anyone can tell where I place it, even if they are watching.
This brings up a third issue. Burying several targets in a field will likely leave evidence as to where they are buried. One obvious solution is to "age" the field. That is, wait several weeks until the evidence is gone. Problem is, if the dowser pre-scanned the field, then there is a possibility of cheating. When I put up $25,000 in a challenge, I refuse to make "trust" a key requirement for the test. Likewise, I don't expect a dowser to trust me, and I try to design my tests so that trust plays no role.
Another solution is to dig lots of holes (someone mentioned using a coin planter) and only bury the targets in randomly selected ones. But this gets right back to being exactly like the Plate Test.
And where do you bury the targets? The locations should be chosen by a randomized method, to avoid bias. This means dividing the field up into small squares, and randomly selecting squares. Also, if you let a guesser take the field first, then you will need to exactly record his selected locations and remove all traces of those selections before the dowser arrives. That means an extremely accurate method of measuring the locations from a reference point.
Another potential problem is target recovery. Let's say you plant 10 silver dollars. If dowsing doesn't locate them, then you absolutely have to be able to retrieve them, in order to prove they were buried in the first place. So if you do a really really good job of not leaving any traces of burial, then you better not bury them beyond the reach of a metal detector. This, of course, limits your ability to let a field age. If the dowser has pre-scanned the field, and you have to leave it for 2 weeks with the targets easily detectable... well, like I said, I'm not interested in putting my money up against someone's honesty.
Finally, what are you judging against? The guesser? How much better does the dowser have to do? One better? Twice better? 3 or more? You need a threshold. This, again, gets back to calculating the probabilities of guessing and placing the threshold higher, exactly as I do in the Plate Test.
One reason I bring all this up because I have actually been presented with a request for such a test. The claimants wanted me to bury a single target in a 10-acre the field that they would get to pre-scan. They also insisted that a witness of their chosing get to watch me bury the target. That requirement was obviously not going to happen. Unfortunately, they weren't willing to work out anything we could both agree on, so it went nowhere.
So, yes, a Field Test is a possibility, but it will be difficult to work out so that it 100% fair, and trust is not a requirement. It can also be expensive and difficult to execute. That's why I use a Plate Test as a standard test; it's easy to do. And, if dowsing works, success should be remarkably easy. But I would be willing to explore a field test for the formal Challenge, and would eagerly agree to it for informal testing.
- Carl