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Looking for statistics help

Kate Rauner

New Blood
K
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Hi all - I'm a new member of the forum - I'm looking for statistics help. A friend of mine is convinced he can dowse water and wants to test his ability. I agreed to help him and I want to do a good job. I'm thinking of having 6 identical new buckets, six numbered spots in a row or circle (previously dowsed as having no interference), one bucket will have water. I'll roll a die and record the number, move the water-bucket to the designated location, move all the buckets slightly so he can't tell which was moved, retreat from sight, let him dowse and record which spot has the water. Then he retreats from sight... repeat the trial.

My question is - how many trials should I run to get sufficient results? Something that would suggest to you-all, who are familiar with these sorts of trials, that there's a real effect and not just a couple random correct guesses?

Thanks for the help! :)
 
Does the dowser have a claim of his success rate? If he thinks he's 100% successful, then six trials in a row would have less than a 1 in 1,000 chance of hitting all six.

By the way, how are you concealing these buckets? It would be sort of obvious which bucket had water if they all weren't concealed.
 
He basically says 100% for "shallow" water. But that's a good point - I must ask him what success rate he expects. As to the buckets - I have two thoughts - in both cases the buckets would be opaque with lids. Maybe fill them all with sand and add water to one (confirming with my friend he can dowse it. Or, place a mason jar or similar sealed container of water in one, then place on the lid. We'd all have to be sure the water wasn't visible in any way.

BTW - I was hoping to use my windowless garage as the test location - there are two doors so we'd never see each other. But my dowser says concrete interferes, so no good. (Oh - and I hope to draft a couple more friends to be data takers/confirmers.

Any other tips anyone has are appreciated. As I said - this is a friend and I believe he's sincere, so I want to do a good job.
 
I am sure you have a rough idea of what the protocol will be. However make sure that in the concealment, ensure that there are no "give aways". Splashes around the concealed bucket etc.
Also ensure that the testee is fully satisfied with the aparatus. Like choice of vessel etc. Dowsers who fail miserably have excuses ranging from interference from the material of the vessel, to the negative vibrations from skepticism.
 
Here is a better idea I think. Obtain six containers to hold water and or sand. Hide them in cardboard boxes and set them on the lawn after the dowser agrees there is nothing to interfere with the test.

Tell the dowser that any number of the containers might contain water, do not say how many contain water, but it would be a good idea to have one that does. Don't allow the dowser or the data takers to observe the preparations of the test area. You should be out of sight during the test also as not to give anything away.

You and the dowser should be able to agree on how many he is able to get right to pass the test. Do several stages with a rearrangement of the sand and water containers each time.

Ranb
 
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Also what constitutes a positive identification. Wasn't there a dispute during some test when the dowser insisted that a brief pause beside the bucket containing water should be counted as a positive?
 
Good points - it wouldn't be worth doing if negative results are hand-waved away. Since we live close by each other, we can do as much preliminary work as needed to satisfy us both. Thanks.
 
Remember to conduct an open test, too: Give the dowser a few runs with the set up where he knows exactly where the water is. This helps rule out the excuse that the protocol interferes with the dowsing ability.

I favor an arrangement with 6 water containers (gallon milk jugs will do), only one filled with water, then all 6 concealed under identical boxes. There are far too many possibilities for visual clues you may never think of, so pay extra attention to the need for complete concealment.

ETA: and as others have mentioned, the dowser's choice for which box conceals the water must be clear and explicit.
 
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I like the gallon jug - it could be filled, sealed, and wiped dry well in advance. And the test runs on the day of the trials, to be sure nothing has changed that would upset dowsing abilities. Thanks
 
Kate Rauner said:
I like the gallon jug - it could be filled, sealed, and wiped dry well in advance. And the test runs on the day of the trials, to be sure nothing has changed that would upset dowsing abilities. Thanks
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I'd put the jugs under cardboard boxes, just to be safe.

Bankers boxes from an office supply store should be more than sufficient.
 
This is a great example of why this is the wrong forum for such questions.

jsfisher said:
Does the dowser have a claim of his success rate? If he thinks he's 100% successful, then six trials in a row would have less than a 1 in 1,000 chance of hitting all six.
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His expectation of success is irrelevant, I expect the question really is "do his choices/results improve over chance", and if there are only two states (water/no-water) then in six samples give only 2^6 or 64 outcomes.

You have a 1 on 64 not a 1 in 1000 chance of randomly getting 100%.

--

This is really a design of experiment, not directly a stats problem.
 
stevea said:
His expectation of success is irrelevant, I expect the question really is "do his choices/results improve over chance", and if there are only two states (water/no-water) then in six samples give only 2^6 or 64 outcomes.
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The question is completely relevant if the goal is show the dowser doesn't have the ability he claims. If, for example, the dowser claims only a 51% success rate, quite a few trials will be required to show anything statistically significant.

You have a 1 on 64 not a 1 in 1000 chance of randomly getting 100%.
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The original experiment was to have 6 choices, not 2, so there'd be a 1 in 6 chance each trial. 1 in 66 chance of being correct for all 6 trials if no dowsing ability be present.
 
jsfisher said:
The original experiment was to have 6 choices, not 2, so there'd be a 1 in 6 chance each trial. 1 in 66 chance of being correct for all 6 trials if no dowsing ability be present.
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That's why I always carry dice that have e sides. It makes the calculations so much simpler.


ETA: You have no idea how much I wish I understood this joke.
 
I predict that after a negative result the dowser will remember that it only works with running water, or the water needs to be underground, or...
 
One thing mentioned earlier which was close to a throw away line was to use a blinded third party to confirm which container was chosen, so that you would be at arms length from the dowser selection.

I think that this part of any test would be essential.

Norm
 
The preliminary open test mentioned by jsfisher is essential. The dowser needs to be sure that his rod (or whatever it is he's using) responds to a position where he knows there's water and not to a position where he knows there isn't before he tries to dowse the unknown positions.

And a good way to get the required odds against chance success, as also already mentioned, is for the dowser not to know how many of the positions have water in them, though there should be at least one.
 
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Pixel42 said:
And a good way to get the required odds against chance success, as also already mentioned, is for the dowser not to know how many of the positions have water in them, though there should be at least one.
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A possibility since you're using 6 options and a die: roll the dice once to see how many will have water, then roll again for the locations. Could still be pre-prepped, you'd just need 6 water-filled jugs and 5 empty ones.

Also, if you'd like to use more than 6 containers, a lot of hobby game stores will sell 8, 10, 12, and 20 sided dice. 10 options would lead to easier math in the statistics :D
 
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