Natasha Demkina, a young girl living in Saransk, Russia, began to receive a lot of media attention around the middle of last month. It started with an article in Pravda, which hailed her as the 'Girl with X-ray vision'. You see, Natasha possesses the unusual ability to peer through human flesh and spot diseases and injuries that are lurking unseen within people's bodies. Or, at least, this is what Pravda claimed. It didn't take long for more newspapers to catch onto the story. The British *Sun* has been the most relentless about pursuing it. They've actually flown Natasha to London and are now parading her around like some kind of weird curiosity. Does Natasha really have x-ray eyes? Well, I doubt it. But I'm sure *The Sun* is going to milk this for all it's worth.

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The next day, the doctor had a high-resolution scan on a 3d imager. Not one of the ailments Natasha mentioned showed up. (These included gallstones; unfortunately I can't remember the others.) However, the scans did show another problem, which Natasha didn't notice, which the doctor is now receiving attention for.

Once again Wiseman cheated by moving the goal posts....... and even then this girl scored 4 out of 7 and odds were 50 to 1....... did they conduct more test, did they treat her fairly not a chance they did. SCICOP are debunkers and will never be fair open and honest to a psychic

I don't have x-ray vision myself, but I CAN see aura's around people and I often can feel other people their feelings. Without prejudice.

I respect every one as the person they are, but that doesn't mean I musn't question their beliefs. It feels good to tell everyone about my experience, without losing respect. Their is more between heaven and earth! It's time we let go of our fears, because they cause the destruction of this world. We have to take risks, discover the unknown!

Byebye, Marlon

Randi tried it on TV in England a year ago and was a complete failure..... Cold reading does not compare to the real deal.......... And Natasha has proved in the that her Disgusting treatment did not stop her getting a 50 to 1 result......... way above chance and Wiseman has got himself into big trouble over his moving goal posts over it. He is now being discredited all over the world. See Professor Brian Josephsons website.......

http://www.csmmh.org/demkina

That was funny...

That well-known TV doctor in England still says Natasha Demkina's psychic diagnoses are amazingly accurate -- despite the fact that her reading of him scared him into getting a colonoscopy and other invasive and expensive medical tests, which showed the abnormalities Ms. Demkina "saw" were not there. I suspect they examined the wrong part of his anatomy.

I think things will become more clear when more cases like Natasha show up in the media. I'm certain that will happen sooner or later.

Bye bye

To get the first one precisely right (ie, matching the right person to precisely condition) is 1 in 7. You now have 6 people left. Picking another precisely is now 1 in 6, and so on ... 1 in 5 and 1 in 4.

A warning here: this is where they made their mistake This is NOT a lotto style draw. In which case she would only have had to pick the 4 people that had the 4 conditions, not which person had which condition.

Try it yourself. Take 7 scrabble tiles, letters 'A' through 'G'. Turn them face down and get someone to muddle them up. Pick a tile and predict what letter it is. Do that six more times. You may NOT guess the same letter twice. Record how many you get right out of 7. Now reset the game and try again and again, recording your results for each game. You could do that a hundred times and you'd never be able to get a count of 4 right (well, there is a slim chance).

The chance of getting 4 exactly right out of 7 in a blind non-return test is (1/7)*(1/6)*(1/5)*(1/4) = 1/840.

In addition to this rather rudimentary statistics, even if the result WERE 1 in 50 (which it is not) the result would still be significant, 2% likely, which is very low and not very likely by pure chance.

As I stated before, she was robbed.

I asked Ray Hyman, Ph.D., professor of psychology at the University of Oregon in Eugene, to help me correct Puck's confused thinking. Prof. Hyman did the original calculation of the odds for the Natasha Demkina test. Those calculations were later confirmed by Prof. Richard Wiseman and others -- including one of our critics, Nobel laureate physicist Brian Jospehson. Here is Prof. Hyman's reply, including reference works for those who would like to verify the calculations for themselves:

"Statistics and combinatorial probabilities can mislead even the brightest people into terrible boo-boos. In the present case, the self-assured critic has made two serious blunders. He has misconstrued the problem. The problem we are dealing with is known as the matching problem. The mathematics for calculating the correct odds is not self evident. Indeed, it is very complicated. I painstakingly worked out the correct probabilities using the formulae in Frederick Mosteller's Fifty Challenging Problems in Probability With Solutions. I believe this is still available from Dover Books. The critic might find it useful to carefully follow the argument in this book. My other source was Hoel, P.G., Port, S.C., and Stone, C.J. (1971). Introduction to Probability Theory. This latter source provides some useful approximations for those who do not have the patience to calculate the exact probabilities. Richard Wiseman was able to check my probability calculations using tables provided by the Journal of the Society for Psychical Research. Our probabilities agreed.

The second mistake this critic makes is to use the probability for getting exactly four correct matches. The number that is relevant for our test is the probability of getting four or more correct matches. Contrary to this persons assertion, the probability of getting exactly four matches in our test is .01533 and not 1/840 (.0012) as he claims. The relevant probability is the probability of getting four or more correct matches which is .01899 (rounded to .02 or 1 in 50).

"I do not have time to give a lesson in probability theory and the matching problem, but let me give a simple heuristic example of how this person's approach provides a misleading answer. Assume we have three subject with conditions A,B, and C. And assume that Natasha's corresponding matchings can be designated a, b, and c. A correct match would be one where she assigns a to A, or b to B, or c to C. For this simple example, we can enumerate all the possible matching attempts. Once we get to four or more subjects, the enumerations become unwieldy."

[continued]

"Here are all the possible matching attempts that Natasha could make in the present example:

Subjects:

Correct Probability

0 36.79%

1 36.81%

2 18.33%

3 6.25%

4 1.38%

5 0.42%

6 0.00%

7 0.02%

-------

Total 100.00%

Note: There is no chance of getting 6 right because in that case you would actually get all seven right.

The probability of Natasha getting 4 or more exactly right is 1.38 + 0.42 + 0.02 = 1.82% or 1 in 55. But that is if she had 7 medical conditions and 7 people to assign them to. There were only 6 conditions and 7 people (one person had no condition at all). When you redo the calculations with that information you get the following table:

Correct Probability

0 42.09%

1 36.74%

2 15.77%

3 4.37%

4 0.89%

5 0.12%

6 0.02%

-------

Total 100.00%

The probability of Natasha getting 4 or more conditions exactly right is 0.89 + 0.12 + 0.02 = 1.03% or 1 in 97.

In addition to this, there is scientific and statistical method to be considered. First is the 'null hypothesis', which in this case would state that, all things considered, Natasha is no different from any other person. To check this we run a test and we use an alpha level (a cut off point) to excluded the null hypothesis. The usual alpha level (commonly used in normal statistical analysis) is 5%. CSICOPS believed they set their alpha level at 0.44% (which was actually 0.14%) (at least 5 right out of a possible 6) which is extremely harsh in my opinion in either case.

Natasha achieved 1,82% on their table, actually 1.03% on my table (at least 4 right out of 6). That is extremely unlikely by pure chance if she is an ordinary person. The expected number of correct answers for a normal person would be no more than 2. Try it yourself and you will see. Either way it is better than 5%.

The calculations posted previously were erroneous, but the ones here have been double checked and I am very confident in them.

This is the program used to generate the tables in this letter (please consider it public domain):

----------------------------------------------------------------------

#include <stdio.h>

#include <stdlib.h>

int main(int argc, char *argv[]) {

int i;

int j;

int tmp;

int count;

int choice;

int actual[7];

int guess[7];

int result[8];

// Initialise

srand(time(NULL));

for (i = 0; i < 7; i++) {

actual

= i + 1;guess

= i + 1;result

= 0;}

result

= 0;// Play ten million guessing games

for (j = 0; j < 10000000; j++) {

// Randomise conditions (actual)

for (i = 0; i < 7; i++) {

choice = rand()%7;

tmp = actual[choice];

actual[choice] = actual

;actual

= tmp;}

// Randomise conditions (guess)

for (i = 0; i < 7; i++) {

choice = rand()%7;

tmp = guess[choice];

guess[choice] = guess

;guess

= tmp;}

// How many were right guesses?

count = 0;

for (i = 0; i < 6; i++) { // 6 conditions only

if (actual

== guess)count++;

}

// Record results

result[count]++;

}

for (i = 0; i < 8; i++) {

printf("=\t\t%8.8g%%\n", i, result

,((float) result

)/100000.0);}

return 0;

}

----------------------------------------------------------------------

Natasha had to match 7 conditions to the 7 subjects, not 6. The 7th condition was "none of the specified target conditions." The odds, rounded off, of getting at least 4 matches correct are .02 or 1 in 50.

Puck is equally wrong to dispute the required level for passing which all parties in the test had agreed to 5 days prior to the test. The well-known principle, "unusual claims require unusual amounts of evidence," certainly applies here. In is not reasonable to use .05 as a maximum probability for passing with such a highly unlikely claim.

Furthermore, these odds are the odds for matching at least 4 conditions correctly by blind guessing. But Natasha wasn't blindly guessing. She had many clues that may have helped her increase her score of correct matches.

We wanted to conduct a truly blinded study, but for unexplained reasons, Natasha has to be able to see her subjects with normal vision. She can't use her "x-ray vision" in the dark. And, although her "x-ray vision" allegedly penetrates any kind of fabric worn by a person, for unknown reasons, she can't "see" through fabric if it's in front of a person (like a screen) instead of on the person. -- ASkolnick

If you aren't going to use scientific method then you can make any claim you like, which you have done. What would have been more fair was to let her try it 20 times with 20 groups of people. That's stats!

I did the test myself 6 times and got 3, 0, 0, 0, 0 and 0. The 3 was a real fluke and it surprised me. I suggest that our readers try it for themselves and they will soon see.

The claim that "unusual claims require unusual amounts of evidence" is an attrociuos misuse of statistics and is unscientific. You can disprove anything using that premise just by setting your alpha level at an almost impossible level.

The chance of her getting 4 right out of 7 is about the same as winning on the long odds in a horse race (50 to 1).

Andrew Skolnick's alpha level around 0.5% (rounded up) or about 1 in 200. That is a mathematically provable fact. This isn't rocket science.

First Puck comes along and claims Natasha was "robbed" and that we're either idiots or trying to deceive you because the odds of her correctly guessing 4 or more matches was really 1 in 840.

Then he says it was 1 in 97.

Now, unable to deny that the actual odds are, as we reported, 1 in 50, he's switching his attack to claiming the passing score was set too high.

Puck, your opinion of whether the passing score, which was agreed to by Natasha and her represenetatives, was too high is no more credible than your previous false statements about the statistics. You best return here under a new screen name because this one has been pretty much discredited. --ASkolnick

Also, I believe that you were out of line, Andrew, for saying that Puck has been discredited. Just because he may be wrong about this problem doesn't mean that he's wrong about anything else.

When that claim was discredited, he claimed that the odds were 1 in 97. And finally, when he was compelled to admit that the odds we gave are correct, he made no apology for his false statements, nor withdrew his highly incendiary claim that Natasha was "robbed." Instead, he simply switched his argument to claiming that the test's "alpha level" was set too high. That, of course, is equally untrue.

Puck's position is that we're wrong about our statistics and he has resorted to several false arguments to promote that position. I don't know about you, but I try to learn from history. And what I've learned from Puck's past statements is that he is not a credible authority on statistics.

Credible people fit their opinions to the facts. People who are caught REPEATEDLY trying to twist the facts to support their opinion are simply not credible.

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