Slashdot Mirror
Statisticians Uncover the Mathematics of a Serial Killer
Hugh Pickens writes writes "Andrei Chikatilo, 'The Butcher of Rostov,' was one of the most prolific serial killers in modern history committing at least 52 murders between 1978 and 1990 before he was caught, tried, and executed. The pattern of his murders, though, was irregular with long periods of no activity, interrupted by several murders within a short period of time. Hoping to gain insight into serial killings to prevent similar murders, Mikhail Simkin and Vwani Roychowdhury at UCLA built a mathematical model of the time pattern of the activity of Chikatilo and found the distribution of the intervals between murders follows a power law with the exponent of 1.4. The basis of their analysis is the hypothesis that 'similar to epileptic seizures, the psychotic affects, causing a serial killer to commit murder, arise from simultaneous firing of large number of neurons in the brain.' In modeling the behavior the authors didn't find that 'the killer commits murder right at the moment when neural excitation reaches a certain threshold. He needs time to plan and prepare his crime' so they built delay into their model. The killings eventually have a sedative effect, pushing the neuronal activity below the 'killing threshold' – which is why there are large intervals of time between groups of murders. 'There is at least qualitative agreement between theory and observation [PDF],' conclude the authors. 'Stats can't tell you who the perp is, but they're getting better and better at figuring out where and when the next crime might happen,' writes criminal lawyer Nathaniel Burney adding that 'catching a serial killer by focusing resources based on when and where he's likely to strike next is a hell of a lot better than relying on the junk science of behavioral profiling.'"
...Is a few bodies of specific height, weight, and coloration.
Numb3rs already. Yawn.
...is another series of murders to consolidate the theory.
Any takers?
Operation Guillotine is in effect.
just needed to get laid often enough so that his neuronal activity stays below the 'killing threshold'.
Sleeping with serial killers saves lives!
You can never know everything, and part of what you do know will always be wrong. Perhaps even the most important part.
in the library with the pencil
Aren't they jumping the gun a bit?
and this shows why mathematical formulas are hard for this sort of thing. Does the formula take into consideration that living in a dead boring town with nothing except churches and no jobs or money might've given this nut little else to do? Maybe if this parasite was born in a big city he would've been more busy with work and murdered less frequently due to being preoccupied with other things?
Minority Report is gonna be real!
Not soon but it WILL be!
different people are... different?
If you look hard enough you can always find some function that correlates to a single set of data. Like the analogy in a beautiful mind, you can find any pattern or picture in the stars if you look hard enough.
catching a serial killer by focusing resources based on when and where he's likely to strike next is a hell of a lot better than relying on the junk science of behavioral profiling.
I am so disappointed. This took all the fun out of "Silence of the Lambs" and a succession of TV shows
The 'murder probability' comes from a probability density function spanning three years, and is estimated from 53 data points, all from the same subject. That is hardly reliable.
And if we take the sparsity of the data for granted, what is the conclusion? That the less frequently the murderer acts, the less likely he is to act, and vice versa. It is a descriptive model, you can not predict the time of the next murder with it.
I think the importance of what they found is overstated. The fact that a murderer's patterns fit a power law is not particularly helpful in really pinning down the time of the next murder. "The expected time of the next murder is a distribution of odds along this curve" is not particularly useful in trying to stop a single crime. Power laws are more useful predictors when applied across populations.
While unlikely to ever be predictive, this result is more interesting from a more academic perspective. It could help illuminate what might be going on in the brain of a serial murderer. Learning how damaged brains function (or fail to function) has long been a means of studying how non-damaged brains may work.
So this might provide some insight into how a compulsive thought builds up in the brain, but it's unlikely to ever allow a profiler to say "stake out this intersection on this night".
I have one, however will not publish till final proof. I like to be accurate about these things.
A closed mouth gathers no foot.
Just watch this this.
For behavioral profiling being a "junk science" they've had a lot of successes, and more success than this idea will ever yield (especially since it's so easily reverse engineerable, not to mention vague in its predictions). And the criticism coming from a criminal lawyer - well, I think the lady doth protest too much.
The basic idea of profiling is to narrow a large search down into a smaller one. The basis of the idea that by studying known offenders and finding commonalities between them, you'll have a clue as to the sort of person a perpetrator will be given an arbitrary new crime. Now that enough information about profiling is out there, offenders can and do reverse engineer the profiling process to make it tougher for them to get caught (assuming they are smart enough to do so - many are not that smart). However, at the very least there will be certain things that they are compelled to do otherwise the crime is simply not interesting for them to do. And certain things they have to do to carry out their crimes which will give a clue as to who they are.
The way I look at it, the people who study these particular criminals and offer advice for catching them are analogous to specialist doctors. For example, if you are trying to diagnose and treat some specialist skin condition that is very rare, you will have better results with a referral to a dermatologist than having the GP struggle and try to treat it as best he can.
If I have seen further it is by stealing the Intellectual Property of giants.
Was this the one protrayed by Malcolm McDowell? I don't know if anyone here has seen that... I think he was the only recognizable one in that film.
WARNING: Smartphones have side effects--most of them undocumented.
Oh man, I get so bothered when someone presents interesting data - only to append a theory that isn't connected to it.
Why is that? Don't you get to publish unless you have a theory, no matter how unrelated an implausible it is?
Human sciences especially - it's understandable though, as it's hard to read people's minds.
Neurons firing? Really?? Does fantasizing about objects we can actually see and touch suddenly make it science?
If the study included brains scans or something, sure. But all they did was look at numbers.
If you don't have a theory that's related to your study, just post your data and spare us your fantasies. Thank you.
No sig to see here. Move along.
And in other news, police warn that the Sudoku killer will kill either 1, 4, or 9 victims next.
Here is the abstract of an article, "Power-Law distributions in empirical data" by Clauset et al (2009):
"Power-law distributions occur in many situations of scientific interest and have significant consequences for our understanding of natural and man-made phenomena. Unfortunately, the detection and characterization of power laws is complicated by the large fluctuations that occur in the tail of the distribution—the part of the distribution representing large but rare events— and by the difficulty of identifying the range over which power-law behavior holds. Commonly used methods for analyzing power-law data, such as least-squares fitting, can produce substantially inaccurate estimates of parameters for power-law distributions, and even in cases where such methods return accurate answers they are still unsatisfactory because they give no indication of whether the data obey a power law at all. Here we present a principled statistical framework for discerning and quantifying power-law behavior in empirical data. Our approach combines maximum-likelihood fitting methods with goodness-of-fit tests based on the Kolmogorov-Smirnov statistic and likelihood ratios. We evaluate the effectiveness of the approach with tests on synthetic data and give critical comparisons to previous approaches. We also apply the proposed methods to twenty-four real-world data sets from a range of different disciplines, each of which has been conjectured to follow a powerlaw distribution. In some cases we find these conjectures to be consistent with the data while in others the power law is ruled out."
So, I would recheck this guy's analysis.
Pickup the pattern of other randomly chosen serial killers and see if they also fit the same mathematical model.
Only then this paper would be worth looking at.
Frankly, I am surprised how they developed and published this model with just a single data point !
I wonder how they got their hands on the brain activity data of a serial killer in action?
Given any dataset, you can come up with a formula that would match it.
That doesn't mean though that if they tried doing this back when he was on his 3rd or even 20th murder, they'd have managed to come up with something useful.
So all it takes to profile a serial killer is, well, build a regression model upon a small sample of, let's say, 50 slayings. Hooray statistics - real science!
Thats just messed up. Why not get off by taking up skydiving, mountain biking, or bungee jumping off the Macau tower? He must have had a pretty f*** up upbringing (in addition to genes the somehow didn't checksum). Oh yeah, in Soviet Rusia it would be hard to leave the USSR or even know about such "bourgoise" activities...
The laugh track completely kills it.
It seems to aim for somewhat intelligent jokes and at the same time insults its audience by telling it when to laugh.
Makes you wonder if this might be fertile ground for (non-government sanctioned) serial killers as well, given that people no doubt disappear all the time and no one is foolish enough to ask about them. Chikatilo might turn out to be a piker.
like the way most people do statistics?
1. Take a hard science like math. ......
2. Add a bunch of highly subjective parameters and tweak them until you get the results you want.
3.
4. Profit!
In other words, give a criminal a brain pacemaker and he will never commit crimes again.
You don't build a statistical model off of a single person.
Troll is not a replacement for I disagree.
First of all, data from one sample does not a statistical analysis make.
Second of all, the curve doesn't even fit all that well. There is significant error in most of the points.
I don't understand how or why so many people fuck up the word "effect." Affect doesn't even sound right when it's used improperly. There is no similarity in definition between the two. Just a similar sound.
Fucking idiots. Slashdot = stagnant.
I don't know if Chikatilo was a psychopath, anyhow, psychopaths seem to enjoy hurting others and are usually pretty smart. There is a secure institution where a buch of psychopaths managed to get hold of the manual for a well known profiling instrument that, effectively scored psychopathology from 0 to 40. They then had t-shirts printed with just "Perfect 40" on them. Point being that once something is public knowledge the kinds of people who engage in this kind of activity are likely to pay attention and work to throw predictive algorithms off, simply because they would gain a great deal of satisfation doing so.
This is nice and all, but how many people need to be killed by a serial killer in order to get a sufficient data set to mathematically model his killing pattern?
knowing a likely area within a couple of suburbs and a time within a couple of months could well be enough for police run undercover operations.
It sure could.
I saw no indication even IF they could predict when a murderer might strike next, they would have any idea whatsoever as to location.
I see no useful narrowing down at all even if they manage to refine the technique.
"There is more worth loving than we have strength to love." - Brian Jay Stanley
So I have had half a dozen Tivos, lots of them have been networked on my home LAN. I have several 2 Tb drives on my home machine, after Tivo Desktop pulls the shows, I have VideoRedo automatically mark the commercials, cut them and then dump another file in MPEG format sans commercials for long term archiving.
Content Producers get paid by networks, networks get paid by advertisers. I pay Comcast a large sum of money every month for content, they in turn pay networks for access to that content. The Content Producer gets no cut of the Comcast money, but he's already been paid to produce a show carried on a major network. Whenever that stops being enough, the Producers will move to other businesses or start another business model like making content directly for Netflix for Amazon.
I have battled pornography addiction for many years. I go OK for a week, and then it starts to get a bit easier, then I go for several weeks, and it gets more difficult. Eventually I crack. Then I "use" several times over a few days, and the cycle starts again.
Substitute "porn use" for "murder" in this, and I know the feeling..
The basis of their analysis is the hypothesis that 'similar to epileptic seizures, the psychotic affects, causing a serial killer to commit murder, arise from simultaneous firing of large number of neurons in the brain.' In modeling the behavior the authors didn't find that 'the killer commits murder right at the moment when neural excitation reaches a certain threshold. He needs time to plan and prepare his crime so they built delay into their model. The killings eventually have a sedative effect, pushing the neuronal activity below the 'killing threshold' – which is why there are large intervals of time between groups of murders.
The "delay" they discuss, due to time needed to plan and prepare, could also be attributed to resisting the urge, until it becomes too much.
And, just in case their are any vigilantes here, my porn is strictly legal, even "normal". I just wish I didn't need it.
A twelve step program is helpful, but I'm still struggling.
Incidentally, there was a pretty decent movie with Stephen Rea and Donald Sutherland about the hunt for Chikatilo called Citizen X.
Sorry, but, hand-waving at neurons to justify the power law they found is none the less also....
"relying on the junk science of behavioral profiling"
Is there an acceptable frequency for murder? Does it grow more acceptable as its frequency is lower?
Sometimes, some mathematicians scare me.
Really? you don't see the difference? assuming you aren't a troll, what are you not getting? When you get content from your Tivo -- like say, a season of Numb3rs from Netflix, to kinda stay on topic -- the studios were compensated by Netflix. fwiw, Netflix paid over US $2B in licensing fees for the content they provided in 2011, and they will be paying 10X that amount in 2012. In contrast, the studios received zero compensation from the thief that provided you a torrent of that same season of Numb3rs. This is not rocket science, dude -- you do understand that copyright owners are entitled to compensation when somebody produces a COPY of a copyrighted work, right? If you don't understand this basic concept, you might as well stop reading now.
Also, why are you are trying to make a distinction between a performance and the COPY of a performance? It is a distinction without legal merit. Copyright holders are entitled to compensation for the use of their copyrighted work whether it is for a live one-time performance, but also if the copyrighted work is ever COPIED for any reason, like for rebroadcast. That is why it's called the copyright -- you don't have the right to copy it if you don't own the copyright.
And while it may be true that "most people" don't call time- and format-shifting piracy, the courts in the US have a very different opinion when it comes to copyrighted content on a DVD. Under the fair use doctrine, there exist specific, limited exceptions to the exclusive nature of the copyright, and in Universal v. Sony Corp, time-shifting was found to be fair use, but if you try to offer fair use as a defense for being caught in possession of say, a torrented season of Numb3rs that you format-shifted to your iPhone so that you could watch it in the morning on the bus on your way to work, you *will* lose, and you will (rightfully) be called a thief for the rest of your life.
This seems to be a re-interpretation of what is essentially addiction behaviour. When I'm obssessed with a game I'll play it for several nights in a row until my interest is sated, then I won't touch any games for a long period of time.