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Posts Tagged ‘psychic’

Sylvia Browne has died.

Spend more than a few minutes looking into the kind of thing she devoted her life to, and it’s hard to avoid the conclusion that she was pretty much one of the worst people it’s possible to be, driven by only the ugliest of human faculties and emotions.

We don’t need to forget or ignore this fact now that she’s gone, but neither is there any need to take joy in the news. Wishing suffering or vengeance on any part of the world only makes it darker and less lovely to be in. And death is still a far greater enemy than Sylvia Browne ever was, no matter how much she twisted it to her advantage over the course of a long and horrid career.

Some people will be personally saddened by Sylvia’s passing; they have my sympathies, even if I can’t honestly join them in their mourning.

For many, the news is a prompt to remind the world at large about this woman’s utter lack of psychic abilities, and the importance of learning how to avoid being taken in by obvious scams, swindles, and other misrepresentations of reality. I’m all for this, but I hope one thing that doesn’t get lost is the point that not everyone with the “wrong” belief in psychic powers is like this.

Some folk believe (incorrectly, sure) that they have some kind of power or gift, and are moved to try to help people, feeling a deep and sincere concern for the well-being of their fellow humans, rather than simply emulating the flimsiest charade of humanity. There is absolutely a non-null intersection between compassion and supernaturalism.

Sylvia Browne was not one of the good ones, by any measure. We can do better than to let any further cruelty and unfair judgment become part of her legacy.

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President Ronald Reagan talked about the importance of “openness to people of all beliefs”, and keeping church and state separate. That was less than thirty years ago. Where will we be in another thirty?

– Misspelt URL aside, this account of a Sally Morgan performance, in which the psychic seemed to be channeling a fictional character (whose details she had been prompted with before the show) is quite damning.

– Newt Gingrich is caught professing entirely unsurprising double standards, hammering Obama for something he never criticised Bush for. His excuse: “I wasn’t a presidential candidate at that point”. But now he is, he needs to play to the extremist Republican base, and to hell with consistency.

– Oh science, what hast thou wrought?

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Psychic Nikki has been “clairvoyant all her life”. She “has appeared on several top-rated international television shows”, and her famous clients include Rod Stewart, Matt Dillon, and Survivor Contestants (I love that guy!)

Nikki has also made some predictions about what’s going to happen in 2012. Why should we trust her, you ask? Well, just look at her track record:

Last year Nikki predicted the earthquake and tsunami in Japan, the Wall Street protests in New York City, the devastating tornadoes in the US mid-west including Joplin, Missouri. She also predicted the deaths of Elizabeth Taylor and Amy Winehouse, the royal weddings of Prince Albert of Monaco as well as the wedding for William and Kate of England, and the trouble in Syria.

Wow, that’s some impressive predictioning there. I mean, those things all did happen in 2011, and how could she have possibly known about them ahead of time unless she were magic?

And looking at that page, it’s clear that she’s expanding on her success this year, and has made even more predictions – one hundred and eighty-six for the year, in fact, not counting the scores of celebrities on a “Death and Health Watch” list. Thanks to Psychic Nikki’s wisdom, we now get advance knowledge of even more absolutely certain future events! Hurrah!

The problems appear when you start paying attention.

If you click the “view my past Predictions” link still proudly displayed on Nikki’s own site, you can see what she actually predicted last year. She makes no attempt to disguise the fact that, rather than limiting herself to the claimed successes mentioned above, she made two hundred and thirteen predictions for 2011.

Here are some things which Psychic Nikki genuinely predicted would happen in 2011, which I certainly don’t remember:

  1. The world’s first brain transplant.
  2. A Hollywood starlet will give birth to a dwarf.
  3. Paris Hilton kidnapped for ransom.
  4. A remake of the movie The Godfather.
  5. A plane will crash into the Hollywood sign in LA.
  6. The royal Crown Jewels will be stolen.

And here are some of her 2011 predictions which are so vague as to be completely useless:

  1. Danger around President Obama.
  2. More UFO sightings.
  3. A space tragedy.
  4. Snookie from Jersey Shore has to watch for injury.
  5. Parts of the polar ice cap will melt.

Hmm. Which are the ones she was claiming she got right, again?

– The “earthquake and tsunami in Japan”. It’s true that she did predict both of these things would happen in 2011. Other locations in which Psychic Nikki predicted earthquakes last year include: the Grand Canyon, Seattle, Oregon, Chicago, Los Angeles, San Francisco, San Diego, Lake Tahoe, Toronto, Quebec, New York, Alaska, Greece, British Columbia, China, Iran, Rome, Naples, Yosemite National Park, and Yellowstone National Park. But… she got the Japan one right, so that’s… something.

– “Wall Street protests in New York City”. There’s no mention of either Wall Street or protests in her extensive list of 2011 predictions. She did claim that New York would face terrorist attacks, a prison riot, an earthquake, and a subway collision. Maybe that was close enough for her purposes.

– “devastating tornadoes in the US mid-west including Joplin, Missouri”. None of her predictions for last year refer to Joplin or Missouri. She did predict tornadoes in California, Oklahoma, Indiana, Texas, Illinois, and Tennessee.

– “the deaths of Elizabeth Taylor and Amy Winehouse”. These two were, indeed, on Psychic Nikki’s “Death and Health Watch”. To give her full credit, so was “North Korean President”, presumably referring to the late supreme leader Kim Jong-Il, who died in December. However, given that there were more than a hundred names on this list, that puts her success rate at slightly below 3%. Also, there’s a disclaimer below the list clarifying that: “It does not mean the above mentioned will all pass but they might have to watch their health and danger in their life”. Which seems to render the whole thing rather pointless.

– “the royal weddings of Prince Albert of Monaco as well as the wedding for William and Kate of England”. Both engagements had already been announced publicly in 2010.

– “and the trouble in Syria”. The only prediction referring to Syria from last year was: “Syria at war with the United States”. I know the US is at war with so many places it can be hard to keep track, but I’m sure I haven’t heard about this one.

When you throw so many random guesses out there as Nikki’s tended to do over the years, you’re bound to stumble onto a few lucky hits now and then, but even considering the huge bulk of her output, the number of successful predictions Psychic Nikki can offer is extremely feeble.

I haven’t even have to do any research to find all this stuff. It’s right there on her own site, the list of current predictions and her many hundreds of misses from past years, all still on display.

But we live in hope. What does she say 2012 has in store for us?

  1. Giant prehistoric Sea Monsters under the sea.
  2. Upheaval in South America with governments.
  3. Somebody will fall off the CN Tower in Toronto, Canada.
  4. More worldwide protests.
  5. Earth will fall off its’ axis a little more.
  6. A hole in the earth’s core.
  7. Space tragedy.
  8. Ellen DeGeneres joining the army for one week.
  9. More makeup for men.

It’s an exciting time to be alive.

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The New York Times faces an ethical quandary. When they’re writing about stuff people have said, should they bother to report on whether that stuff’s true or not? Is that an important or useful part of their role as a news organisation? They’re “looking for reader input” on this. Because they’re not sure.

Dear Dr Phil, if you want to actually help people as you claim to do, you have a responsibility to do better than this.

– A new addition to add to the list of Mother Teresa’s crimes against moral decency: she campaigned to protect a child-abusing Catholic priest, stressing “how careful we must be to guard the purity and reputation of that priesthood”.

Here’s a video which very neatly and briefly explains the distinction between a trend and a variation in data – for example, between the constantly changing weather, and the gradually shifting climate.

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For something that involves so much lying down and making sympathetic faces, looking after a girlfriend with glandular fever can be surprisingly tiring and time-consuming.

So, apologies that I’m still not very present here. However, although I’m not going to comment at length about Sally Morgan today, it’s worth mentioning that Simon Singh is one hell of a gentleman badass.

Is that a thing people say? That should totally be a thing.

Of course Sally Morgan has every right to decline an invitation to any particular event at which certain of her detractors propose to “test” her, especially in a situation which has not been arranged with her and under circumstances with which she may not be familiar or comfortable. But the point Simon Singh and others are making is that she has by no means demonstrated the validity of the numerous grandiose claims she regularly makes, and in which many people become deeply emotionally invested. If she has any interest in the well-being of her fans, or in being intellectually honest, she should really be actively seeking some way to prove her abilities beyond a level which can be replicated by a practised charlatan.

She could also do with cultivating a slightly thicker skin for criticism, if she’s so inclined to send her lawyers after any prominent figure who may be disinclined to accept everything she says at face value.

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One thing that makes the Righteous Indignation podcast stand out – at least among the other stuff I listen to – is the regularity of the interviews they get with non-skeptical types. They’re always friendly discussions, where the hosts mostly just ask questions to establish what their guests believe, and why, and how they respond to some of the common skeptical criticisms.

They don’t hide the fact that they’re skeptics and don’t really believe in any of it themselves, and they don’t hold back from dissecting a ludicrous idea as fully as it deserves. But they manage to keep the chat friendly when somebody’s taken the time to answer their questions.

A great example of this is the recent interview with Vicki Monroe, a psychic medium and “cold case investigator” who’s worked with the police on a number of occasions in this capacity.

Her website is full of the kind of sparkly sappy nonsense you’d expect, and there’s an unpleasant surprise waiting for anyone familiar with James van Praagh if you scroll down a way. But on the show, she was really hard to dislike, and I quickly gave up trying.

For about the first half-hour of the interview, I could only support and approve of just about everything she says. She was warm, she was friendly, she was open, and given that she believes she has this particular power (obviously I don’t believe she does, but simply being mistaken is no crime), she was virtually beyond reproach in the way she operates. She talked, for instance, about how important it is for her not to inject herself into an ongoing police investigation of, say, a missing person, except at the express request of the family or somebody else directly involved.

She specifically referred to the case of Madeleine McCann, the British child who disappeared a couple of years ago in Portugal and got a particular storm of media attention. Vicki’s stayed out of that whole case, because she hasn’t been invited in, and knows the potential that someone in her position has to make things worse for the family, if she were to butt in with her ideas uninvited. Numerous examples of other “psychics” with no such scruples are not heard to find.

She talked about other “psychics” who she felt didn’t respect these kinds of important ethical standards, and recognised the capacity for cons to be pulled on innocent people eager to believe. She even named names, and was barely less scathing about Sylvia Browne than you’d expect from any discussion on a skeptics’ message-board.

And she singled out the skeptical community for praise in their attitude toward psychics, and the importance of skepticism in a subject where fakery and being conned is such a danger.

You have to be skeptical. You have to be!

That’s a direct quote from Vicki Monroe, psychic medium. Not a sentiment you can expect to hear from Joe Power any time soon.

So, I like her. She seems like good people. Of course, on some level it all falls down when you get to that whole pesky psychic powers thing. But that doesn’t stop me from basically liking her.

It’s just fascinatingly bizarre, seeing how it goes wrong.

Because she gave a psychic reading, as part of the interview, to Hayley and Marsh.

And it was terrible.

I have no doubts about her sincerity. I fully believe that she means well, cares about people, and wants to help. I think if you’re a good person, and believe as Vicki does in your own psychic powers, then her behaviour is close to being a solid guideline for how to behave. But the actual efficacy of her abilities, and what constitutes evidence which should be taken seriously, seems to be a massive blind spot for her.

Let’s look at the things she said, when she tried to provide a reading for both the hosts of the interview, Hayley and Marsh, [whose questions and comments will go in square brackets].

I don’t know who has this terrier, it’s a little terrier-type dog… it’s a terrier of some sort, and it’s crossed over…

I’m looking at a dog right now. And I don’t know who it belongs to. Either you, or it belonged to someone in the family… there’s a woman who’s holding it.

This didn’t go anywhere. Nobody seemed to have had a terrier who died. That’ll be a miss.

Michael, did you lose your grandmother on your mother’s side?

Not exactly a stretch to imagine Marsh’s grandmother might be dead, but this was another miss. She mused that the woman she was seeing could be a great-grandmother, and she agreed that guessing that his great-grandparents might have died was hardly a powerful psychic feat.

I’m trying to figure out who Ann is. Or Anna.

[Is it someone who’s alive, or someone who’s dead?]

Alive.

Hayley and Marsh both know someone called Ann or Anna. A modest hit, but Vicki’s admirably quick to avoid taking credit hastily.

She asks at this point, “I mean, who doesn’t know a Catherine or an Elizabeth?”, which I think was to highlight her acknowledgment that simply guessing they might know someone with a fairly common name isn’t a huge deal. (I mention this because, when Marsh was recapping things later in the interview, it sounded like he’d taken her mention of those names as a further psychic guess. I think she was just picking other common names to illustrate a point, and that’s not really a miss.)

I have… somebody saying the name Rebecca for Hayley…

Hayley, do you know who that is?

Hayley says no at first. Marsh mentions that he knows a Rebecca, and then Hayley admits that she also does, distantly. So, if that’s a hit, it’s pretty weak. There are far more prominent people in both their lives which these spirits could be mentioning, if they wanted to be taken seriously.

As Marsh is just about to elaborate on his Rebecca, though, Vicki jumps in again with a question directed at Marsh.

You date a lot, don’t you?

[*laughing* I absolutely don’t.]

Yeah, but she’s right around the corner!

[I think my girlfriend of two years would be quite annoyed if I was dating a lot.]

After these two clear misses, she moves back to the Rebecca connection. Marsh gently suggests that, with all these vague names being thrown out and only occasionally sort of going anywhere, it doesn’t seem to be going that well.

Vicki disagrees. The fact that she’s been able to provide no useful information about the people she’s performing a psychic reading for takes a back seat to the fact that she knows it’s happening. One way or another, she has these spirits talking to her, and she knows she’s not just making this stuff up, so whatever they’re saying must be meaningful in some way.

She’s allowing her subjective evidence to confirm its own validity. It reminded me of something which I’ve heard called the “toupee fallacy”. This is when someone claims to be able to spot when someone’s wearing a toupee, but never checks how accurate they are against any other objective measure. They just sometimes say “Oh, that’s a toupee,” and sometimes don’t, and consider that proof of their ability – ignoring the fact that they might be missing plenty of toupees that aren’t obvious enough for them to spot, and they’d never know it.

Vicki seems to be like that. She’s said nothing close to being specific or accurate enough to mean anything. Testing her spirits against external sources of information – like checking if someone’s really wearing a toupee – is returning almost nothing supportive. But she’s not deterred. Because that’s not how she’s measuring her success.

[Is that the great-grandmother on my mother’s side?]

…The one that I am talking to is the one that says “the one you liked”.

[What’s her name?]

She hasn’t given me her name yet.

[If you were able to get her name, that’d be really clear then.]

…Who’s Evelyn, or Ethel?

[No…]

Note that she didn’t say that Evelyn or Ethel was the name she had for the great-grandmother in question, so she could technically wiggle out of this one being a miss. But it’s not a name that means anything to Marsh, so I’m calling that one a miss anyway. It was supposed to be important enough for one of these spirits to mention it, and it meant nothing.

Then Vicki spends quite a while seeming to regroup, listening to the spirits and muttering the occasional “okay” or similar. It seemed to me at the time like her confidence had been shaken as she realised this wasn’t exactly going well, and she needed a moment to pull herself together. I wouldn’t begrudge her that, but I could be wrong anyway. Her next guess doesn’t sound any more certain:

I’m not sure, because all I keep hearing is “Rita”, or “Anita”… or “Lida”. Something like that. I’m not sure.

She clarifies that this is an elderly relative who’s passed on to the other side, but doesn’t wait to see if this hits home with anyone. Straight away:

Helen, who’s that?

[Again, I know several Helens…]

They’re naming people that you know, because they watch you. They name people that you seem to be around a bit.

Another negligible hit. Anyone could pluck a series of female names out of the air like this, and be sure that a few of them would match up with the social circle of anyone who’s not a total recluse.

Lucille, do you know who that is?

Marsh doesn’t. Miss. He guides her back to Helen, though, who he knows “a bit”. This is Vicki’s idea of “a good validation”.

If there are spirits watching over Marsh, and monitoring his loose relationship with Helen, then it doesn’t seem unreasonable to ask whether they might be aware of Helen’s surname, middle name, birthday, age, star sign, hair colour, home town, relationship to Marsh, favourite colour, or shoe size. If Vicki could provide any of these, or any of a number of other things actually about Helen, then this might validate something. But the fact that her subject has an acquaintance whose name matches one of half a dozen or so she’s put out there is totally meaningless.

Mary? Who’s Mary? That’s a deceased person.

She breaks off in the middle of a sentence here, in which she’d been explaining how it all works and why Helen was such a good validation, to move straight onto the next one. Hayley knew a Mary who is now deceased.

Cancer? Hayley, this was cancer?

No. Miss.

Okay, but she says a sickness.

Yes, Hayley confirms that Mary did die of a sickness. There are other ways to die than by sickness, so let’s generously call that another weak hit.

It feels like it’s a blood sickness, though.

Hayley says no. Miss.

…an infection of some sort.

[Yes, there was an infection.]

Yeah, but it came from a wound, or some kind of a… surgery or something… She’s saying that she developed either a septicemia or a staph infection…

[I don’t think so, no.]

…or a haematoma, or a blood clot. But it was very quick in the end.

[I didn’t know her very well, but I don’t believe it was an infection like that.]

It was a blood infection. You can check that out.

So a sort of hit on the infection, before she started trying to pin down the details. Then suddenly she’s entirely confident that she’s got this one absolutely right, and that any further research Hayley does into Mary’s past will vindicate Vicki’s prediction.

Which seems an odd point at which to start being unshakably confident. Given how much trouble she’s had so far in getting either Hayley or Marsh to recognise any of the names she’s thrown at them, there doesn’t seem to be much basis for the idea that this Mary is definitely the spirit of the first person of that name who Hayley happened to think of.

To her credit, she specifically asks for feedback on this if they ever do look into it further. I have my doubts, though, as to how regularly Vicki adjusts her view of her abilities, based on people coming back to her later with things that didn’t quite pan out.

Who the heck has a pig? That’s what I want to know.

Now we’re getting somewhere. That’s kind of unusual. Most people don’t own pigs. Hayley knows someone who owns a pot-bellied pig. A hit!

And they live in the house? That’s what I’m hearing.

D’oh. Miss. And you were doing so well.

I keep hearing the name Jennifer or Jenna. I feel like that would have been somebody who somebody would have known as a young child.

Yet another common female name. She should’ve followed up with the pig thing. Marsh vaguely thinks he might have gone to school with a Jennifer, but no-one he really remembers. I went to school with a lot of people, including at least one Jennifer, and I’m not alone in this. Another very general guess, and a miss.

Whose grandfather, or great-grandfather, smells like Old Spice?

About four seconds later she kinda answers her own question, when she says: “Back then it was what everybody wore”. Neither Marsh nor Hayley can confirm nor deny that any of their elderly male relatives favoured this particular brand.

And one of them smoked a pipe, I know that.

[Yeah, he did.]

And that has a vanilla scent to it.

[No, I think he just went for straight tobacco.]

No, but to me it smells like vanilla.

[Ah, okay.]

I’m not letting her claw it back there at the end. That’s one unimpressive hit, one specific miss.

And he has a pocket-watch.

A likely hit, but Vicki freely offers that this would also have been common for men of that era.

Hayley, you’ve lost grandparents, right?

[Yes.]

Okay, because there’s a grandmother here… And she says she left you some jewellery?

[Yes.]

And that… do you wear it on a necklace?

[No.]

Or do you wear it on your finger?

[No.]

Same pattern again. A hit on the vague stuff that probably applies to a lot of people, but a complete failure to get any of the details right. Vicki then starts talking about the jewellery in question, asking the spirit what it was (apparently not getting a straight answer) and then describing it, as if she can see it and is trying to think of the name for that type of jewellery.

Is it like a rosary, or something?

“Rosary” was the word she was searching for, while muttering to herself about beads, and it’s a miss. She says it’s very nice, whatever it is, and that the spirit is wearing the same thing.

So she can see this item of jewellery being worn… but can’t tell whether it’s got beads, or whether it’s worn on the neck or the wrist or somewhere else? I don’t understand.

She moves on then to the fact that Hayley likes chocolate, but describes it as “not a psychic thing”, so we can leave that one.

And… that’s it. This section of the interview lasted about 15 minutes, and I’ve listed everything that she got remotely correct. They have another quick chat about how important it is to call out the fake psychics who fool people and take their money, and Vicki agrees that what the skeptics are doing is important stuff.

And although it’s admirable that she can be this self-aware about something that means a lot to her, and recognise that skeptics’ doubt and questioning is often coming from a positive place, it’s so odd seeing the disconnect with her assessment of her own performance. “They think that was pretty good,” she says of the spirits she was talking to, and all the information they provided here.

It depends on quite how you’re counting, but I think my tally gives her 7 very weak hits on things like common names, 1 more specific hit on somebody knowing somebody who owns a pig, 1 not-that-impressive hit on the jewellery, and 14 misses in between.

And the dead relatives, we’re told, are proud of how much they managed to communicate.

Are these visions being obscured by a dry ice machine that the spirits don’t know how to switch off? Are they having to talk through the speaker system from a drive-thru? Why wouldn’t they be able to pass on some information that makes sense, that’s more easily understood, and that refers to something sufficiently specific to the people involved to be impressive?

Right to the end, I found Vicki Monroe to be friendly and likeable. I’m quite bewildered by her belief in herself, and the impermeable field of woo in which her usual appreciation for critical thinking doesn’t seem to apply. But you have to do worse than just be wrong or a bit confused to entirely lose my affection, and Vicki displayed none of the malice or reckless stupidity that’s often evident in her profession.

She genuinely seems interested in the truth more than any self-aggrandising or pushing her own abilities. When Marsh was recapping the list of names she’d gone through, she helpfully reminded him of a couple of the times she’d completely missed. She insists that anyone who has a session with her also makes a recording, so that they can refer back to it later. This helpfully allows her to pass off a lot of apparent misses as “future hits”, in a sense, but I really feel she’s genuinely interested in helping to make as much of a real connection as she can.

These are things that are worth remembering when dealing with somebody devoting their life to something you consider fictitious or illusory. You might be well aware of all the reasons why belief in psychic powers can’t be justified based on the available evidence, but if you forget that other people don’t always see that, then you’re left facing the awkward question of what terrible people they must be to persist in something so obviously bogus. But this is the same fallacy we’re much better at recognising when it’s turned on us.

Religious people often accuse atheists of being angry or resentful or rebellious toward God, missing the point that we don’t believe he’s real. Some psychics or other supernaturalists seem to think that skeptics are just out to ruin everyone’s fun, as if we knew as well as they did that paranormal phenomena exist but for some reason seek to deny it anyway. And for us to assume that every professed psychic is a shameless cynic cashing in on bullshit is exactly the same mistake.

So I make no apologies for saying I still like Vicki Monroe.

Or for saying that she’s utterly unconvincing and tragically deluded.

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Don’t run away.

This post is going to be about maths and probabilit

I SAID DON’T RUN AWAY
 
 
Dammit.

There was a scientific paper recently published, in a respected academic journal, which purported to demonstrate evidence of human precognition.

Yep, science says people can tell the future.

Except, not really. Not yet, anyway. As the study’s author, psychology research Daryl Bem, said himself in the published paper, it was important for other scientists to repeat the experiment, and see if they got the same results. Richard Wiseman has been among those involved in such attempted replications, which so far have failed to support Bem’s original conclusion.

There’s a big moan I’m not quite in the mood to make, about how science generally gets publicised in the media, and the tabloids’ tendency to make a massive fuss over preliminary results, without concerning themselves with facts which later emerge and completely undermine their sensationalist headlines.

But I want to talk about the maths.

Replication is always important in science, particularly where the results look unlikely, or demonstrate something completely new. This is partly because, for all we know, Bem’s original research could have been dishonest or deeply flawed. Most people seem to consider both of these unlikely, though, and I’m certainly not suggesting that he’s faked his results.

But people often seem to assume that these are the only two options: that positive results must mean either an important and revolutionary breakthrough, or very bad science. The idea that something could just happen “by chance” now and then never seems to get much credibility.

Almost every time someone in a TV show or a movie proclaims something to be “just a coincidence”, or that there’s a “perfectly rational explanation”, we’re meant to take it as an ultra-rationalist denial of the obvious – usually supernatural – facts. Remarkable coincidences just don’t happen in the way that ghosts and werewolves obviously do. In fictional drama, there are good reasons for this. In the real world, this is a severe misunderstanding of probability.

When deciding whether or not to get excited about a result, scientists often look for significance “at the 5% level”. Bem’s results, supporting his precognition hypothesis, were significant at this level. But this does not mean, as you might think, that there’s only a 5% chance of the hypothesis being wrong.

What it means is: there would be a 5% chance of getting results this good, just by chance, if people aren’t really psychic.

So, getting results like this – statistically significant at the 5% level – is actually slightly less impressive than rolling a double-six. (If you have two regular six-sided dice, the odds of both landing on 6 on a single roll is 1 in 36, which is slightly less than 3%.)

I’ve rolled plenty of double-sixes. If you’ve rolled a lot of dice, so have you. And if you do a lot of science, you’d expect just as many random chance results to look significant.

So, if you’re thinking that we should probably ask for something a bit more conclusive than a double-six roll before accepting hitherto unconfirmed magic powers, you’re probably right.

This is the essence of Bayesian probability. Imagine having one of the following two conversations with a friend who has two dice:
 
 
“These are loaded dice, weighted to always land on a double-six. Watch.”

“Huh, so they are. Neat.”
 
 
“I’m going to use my psychic powers to make these dice land on double-six. Watch.”

“…Okay, that’s a little spooky, but you could’ve just got lucky. Do it again.”
 
 
You see why you might not believe it right away when your friend claims something really outlandish? But when it was something pretty normal, you’d be more likely to buy it?

In either case, the odds of rolling sixes by chance were exactly the same, 1 in 36, independent of what was allegedly influencing the outcome. But that doesn’t mean you should be equally convinced in either case when the same result comes up.

Both claims become more likely when the double-six is thrown. After all, if the dice really are loaded (or psychically influenced), then what you’ve just seen is exactly what you’d expect to see. But they’re not both getting more likely from the same starting point. One started out as a much more plausible claim than the other, and it’s still more plausible now.

Loaded dice? Sure, they have those. Telekinesis? Well, you have my attention, but let’s see you do it again. And again. And a dozen more times with a fresh set of dice.

This is part of my recurring, occasional project to convince the world that Bayesian probability is both important and intuitive, when it’s expressed right.

Ben Goldacre wrote about Bem’s research, the New Scientist also discussed it, there are some details of the replication attempts at The Psychologist, and I was prodded into thinking about all this in some more depth by a recent episode of the Righteous Indignation podcast.

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Yay, another maths lecture!

Click through to see the whole cartoon at XKCD. Really do it. It’s important. Especially if you want the rest of my burblings to make sense.

So. It’s partly funny because it satirises the sensationalism of tabloid news, and the urge to cram as much excitement into a headline as possible only to leave a sober assessment of actual facts to the blogosphere. But it actually addresses a much more common problem with our understanding of probability.

Most people who pay much attention to any kind of sciencey talk are probably familiar with the p-values referenced in the comic. When scientists are testing a hypothesis, they’ll often check whether the p-value (p for probability) of the results from their experiments is less than 5%. The smaller the p-value is, the less likely it is that their results are purely down to chance.

However, the p-value kinda means the exact reverse of what a lot of people assume it means.

When scientists talk about results being “significant at the 5% level”, say, it sounds like this means there’s a 95% chance of a real connection. In this cartoon’s case, it sounds like the scientists are 95% certain of a link between green jelly beans and acne.

Applicants for James Randi’s million dollar challenge are required to meet rather more stringent criteria, but it’s often expressed the same way. For instance, a dowser might have to psychically deduce which of several sealed containers is the one with water in, and repeat it a number of times, so that the p-value becomes very small. They want to be certain there’s really something going on, and it’s not just chance, before the money will be handed over.

But the intuitive idea of what the p-value means in these cases isn’t quite right.

Here’s what you actually need to do. Assume that there is no connection between the things being tested – jelly beans don’t affect acne, and all psychics are just guessing. Then, what are the odds of getting results at least as persuasive as the ones you saw, purely by chance?

That’s your p-value.

So, a p-value of 5% tells us something useful. It means that the results you’ve got are kinda iffy, given what you’d usually expect, if there’s no deeper underlying pattern there. You’d only expect to see results this skewed about 1 time in 20, if you’re relying on randomness. So maybe something’s up.

But if you do a whole bunch of tests, like the jelly bean scientists did, once in a while you will get some iffy results like that just by chance.

Now, clearly one thing this tells us is to be wary of data which has been cherry-picked, like the jelly bean journalists did. There were lots of negative results being ignored, and a single positive outcome highlighted. But the implications for how we assess probabilities more generally are, I think, more interesting.

In particular, it tells us that how likely something is doesn’t just depend on this one set of results. If a 5% p-value means “we’re 95% sure of this”, then this one study has entirely determined your estimate of the likelihood. It fails to take on board any information about how likely or unlikely something seemed before you started – and often this information is really important.

For instance, say you were studying differences between smokers and non-smokers, and the rate at which they get cancer. Any good analysis of data along these lines should easily pass a 5% significance test. It’s a highly plausible link, given what we already know, and 95% sounds like a significant under-estimate of the likelihood of a correlation between smoking and cancer.

But now imagine you’ve done a different test. This time, you just put a bunch of people into two groups, with no information about whether they smoke, or anything else about them, and flipped a coin to decide which group each person would go into. And imagine you get the same, seemingly convincing results as the smoking study.

Are you now 95% convinced that your coin-tossing is either diagnosing or causing cancer in people you’ve never met?

I hope you’re not. I hope you’d check your methodology, look for sources of bias or other things that might have crept in and somehow screwed up your data, and ultimately put it down to a bizarre fluke.

And it makes sense to do that, in this case, even despite the data. The idea that you could accurately sort people by cancer risk simply by flipping a coin is utterly ridiculous. We’d give it virtually zero probability to begin with. The results of your study would nudge that estimate up a little, but not much. Random fluke is still far more likely. If multiple sources kept repeating the experiment and getting the same persuasive results, over and over… then maybe, eventually, the odds would shift so far that your magic coin actually became believable. But they probably won’t.

And this idea of shifting the probability of something, rather than fixing it firmly based on a single outcome, is at the heart of Bayesian probability.

This is something the great Eliezer Yudkowsky is passionate about, and I’m totally with him. That link’s worth a read, though someday I’d like to try and write a similar, even more gently accessible explanation of these ideas for the mathematically un-inclined. He does a great job, but the arithmetic starts to get a bit overwhelming at times.

And if the thrill of counter-intuitive mathematics isn’t enough to convince you that this is fascinating and important stuff, read this. And then this.

Short version: a number of women have been convicted and jailed for murdering their children, then later released when somebody actually did some better statistics.

The expert witness for the prosecution in these trials estimated that the odds of two children in the same family both dying of cot death was 1 in 73,000,000. General population data puts the overall rate of cot deaths at around 1 in 8,500, so multiplying the 8,500s together gives the 1 in 73,000,000 figure for the chance of it happening twice. This was presented as the probability that the children could have died by accident, and thus it was assumed to be overwhelmingly likely that they were in fact deliberately killed.

But, as we learned with the cancer stuff earlier, we should consider these substantial odds against our prior assessment of how likely it is that these women would murder their children. This should start off minuscule, because very few women do murder their children. The fact that both their children died should make us adjust our likelihood estimate up a way – someone with two dead children is a more likely candidate for a child murderer than someone whose offspring are alive and well, after all – but it’s still far from conclusive.

Another way of expressing the central point of Bayesian probability is to consider the probability of A given B, for two events A and B. In this case, the odds of two children randomly picked from the population both dying of cot death may well be around 1 in 73,000,000 – but given that the children you’re considering both died in infancy, and were both siblings and so might have genetic or environmental factors in common, the cot death scenario becomes far more likely.

I wanted to expand on that last point some more, and touch on some other interesting things, but I’m hungry and you’re bored.

Ha. I said “briefly”. Classic.

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While I was offline for a month, I kept a note of any links and news stories worth commenting on. Now that I’m back, I’m aiming to post two short items a day here, about stuff that happened during my online absence, until I’ve cleared the backlog. This is one of those.


If you were hoping to be told what card you’re thinking of by a carrion bird, I can only apologise for the disappointment.

Evan Bernstein reported recently about a woman who charges dying hospital patients $125 to spin some yarn about “who’s waiting to greet them on ‘the other side.'”

Talk about the repulsiveness of the image of an ambulance chasing lawyer. Well, this is a psychic chasing the hearse on the way to the hospital to pick up the bodies.

Seems an appropriate analogy to me.

There are people standing up for her, of course, and declaring that anyone who won’t instantly believe in these outlandish claims entirely at face value must be living a life with no hope or meaning. Which is bewildering enough, but okay, let’s work with them a bit. Let’s say she’s real, she genuinely has some power to do what she says she does, and she’s making a really, really good living by providing a legitimate service.

Personally, I find that a real stretch to believe. But let’s run with it. Here’s something that’s absolutely not a stretch to believe:

Somewhere, some unscrupulous con artist would read this article, see this woman making a fortune by telling dying people reassuring things, and think: I have got to get me a piece of this action.

This is easy to imagine. There are undeniably people like this in the world, trying to make a fast buck and not caring who they hurt in the process. Some of them rob banks. So why wouldn’t some of them, somewhere, decide that dispensing a few platitudes to some old suckers desperate for some comfort before they pop their clogs might be an easy gig?

And if it’s obvious that there really could be scammers trying to rip people off with a pale imitation of what the real psychics do, how do you tell the difference?

That’s not at all a rhetorical question. I’m not trying to say that you can’t tell the difference between a real psychic and a con artist, and so you’re a fool for believing that any of this is real. It’s genuinely worth considering how to distinguish the two, and avoid falling for someone’s dishonesty.

It’s something so many believers seem entirely unwilling to consider.

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Just a quick link today to a recent confirmation that Joe Power is still an unpleasant, bitter, cruel, spiteful, nasty little man.

Not that we needed any further reminders. Derren Brown has it covered, in particular. But still. He is quite revolting. Even for a fucking stage psychic who pretends to talk to people’s dead relatives.

Sorry to only bring you negativity today. I’m not feeling creative enough for anything more right now. I wrote over a thousand words of my novel earlier this evening, though, which isn’t too bad as excuses go.

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