Decision Science News

THE CENTER OF THE CIRCLE HEURISTIC

When a number of crimes, for instance burglaries, can be linked to the same offender, police often plot the locations on a map. The art of finding the location of the criminal’s home based on the crime sites is a key objective in what is known as geographical profiling.

Snook, Zito, Bennell and Taylor (2005) ran a competition between 11 techniques for locating offender residences. All techniques took as input the x-y coordinates of crimes (all committed by the same crook) on a map and made predictions of the criminal’s home location. There are many ways to turn these sets of coordinates into a point prediction. One stands out as exceptionally simple, so much so that it can be carried out with a pencil and ruler:

Center-of-the-circle heuristic: Predict that the offender lives at the mid-point of the line connecting the two farthest apart crime locations.

The figure up top shows the heuristic applied to a set of crime locations. Note that the midpoint is the center of the smallest circle encompassing all the crimes. Ten other methods for profiling were tested, including other “spatial distribution strategies” such as finding the centroid, harmonic mean, geometric mean, or point of minimum distance. Also investigated were computationally intensive “probability distance strategies” that involve fitting probability distributions such as the negative exponential, normal and lognormal and zooming in on maximally likely cells.

The 11 methods were applied to the crime locations of 16 UK residential burglars who had committed at least 10 crimes. Interestingly, all the strategies were run on a computer except for the center-of-the-circle heuristic, which was applied manually. We don’t know if that is because the crime-fighting software used is not clued into the power of the simple heuristic.

As shown below, in the aggregate analysis, the center-of-the-circle heuristic made the most accurate forecasts of where the criminals lived. In another study (Snook, Taylor and Bennell, 2004), laypeople who were trained with heuristic methods were as accurate at predicting home locations as a computerized geographic profiling system.

Decision Science News’ point is not that highfalutin statistics are bad. In fact, the more complex systems provide information that the “x-marks-the-spot” systems cannot provide, such as probable search areas. The blog merely wishes to observe that it is sometimes difficult to impossible to beat simple strategies at forecasting.

References:
Snook, Brent, Michele Zito, Craig, Bennell, Paul J. Taylor. (2005). On the complexity and accuracy of geographic profiling strategies. Journal of Quantitative Criminology, 21(1), 1-26.

Snook, Brent, Paul J. Taylor & Craig Bennell (2004). Geographic profiling: The fast, frugal, and accurate way. Applied Cognitive Psychology, 18, 105-121.

Notes:
This is extracted from a paper the DSN editor is writing.
Decision Science News does not promote vigilanteism.
Yes, that is a rotated map of Rhode Island.

POSITIVE / NEGATIVE / ZERO SUM ADVICE AND THE JOB MARKET

Every year, Decision Science News republishes this wonderful, caring advice on the AMA (Marketing) job market. Recently, our friend and kindred blogger Andrew Gelman asked how much of the advice is positive sum.  Your humble editor, not knowing much about what positive sum advice is, looked into it.

A cocktail-party-worthy example of things positive / negative / zero sum comes from the entertaining Why Not?: How to Use Everyday Ingenuity to Solve Problems Big And Small by Barry Nalebuff and Ian Ayres, who argue that The Club (a steering wheel lock) is zero sum while LoJack (a chip in your car that reveals its location) is positive sum. Their logic is that The Club simply causes car thieves to chose another car to steal instead of yours. So if you get +1 points for not having your car stolen, some other schlub gets -1 points for losing a car and -1 +1 = 0, the sum of the game. They then argue that LoJack leads the police to the location of the car theft rings, which they can subsequently bust. With the car thieves in jail, car theft overall goes down and the net benefit to society is argued to be positive.

Why Not? is a book we wholeheartedly enjoy and endorse, despite our upcoming diss of one of its points. The authors state that the net value of The Club to society is zero. Not probably zero, but zero. But dear authors, are you sure that people always steal another car upon seeing The Club? Is there a a fixed quantity of crime that each criminal must commit? A law of conservation of crime? In the Club / LoJack example, every criminal either ends up shifting crime to where its easier, or in jail. This blog’s inutition is that some crime just disappears when there are fewer temptations in the environment, much like some overeating disappears when there are fewer oversized portions in the environment. This blog has moved between the US and Europe many times and experienced first-hand the effect of smaller portions on body weight.

(Note also that the conservation of crime idea would suggest that in a fully LoJacked future, the new generation of criminals (or those just spring from the joint) would steal something else. How’s that positive sum?)

Back to the academic job market. Andrew’s comments are indented. The quotes within the indents are Andrew quoting Decision Science News.

If I tell people a secret way to put their proposals at the top of the pile for a granting agency, that’s zero-sum

We will buy that. The way that a stack works, something going to the top position moves the things formerly above it down one position such that the sum is zero. This point will come in later.

Just for analogy, if I give people advice about how to make cleaner powerpoint presentations, that’s positive-sum (better communication for all)

Or is it? Let’s say we were an obnoxious blog. We could then argue that the person who receives said PowerPoint advice benefits and the person who doesn’t does not. To this you might say, yes, but Decision Science News, presenters are not in a fixed sum competition in which one person’s gain is always another person’s loss. But is this true? If I’m in your field and my PowerPoints rock, I may hurt your chances of getting the scarce endowed chair, winning the teaching award, landing the best book contract on our obscure topic, etc.

“Get yourself a room in the conference hotel, preferably on the floor where the express elevator meets the local elevator for the upper floors.”: Zero-sum. If you get a room at the conference hotel, somebody else will have to find a room elsewhere.

Job candidates generally benefit from being in the conference hotel and on the elevator-transfer floor. Regular conference attendees do not benefit from being on the noisy, congested transfer floor, so both win if the job-seekers are on that floor. About conference hotel capacity, every single seeker could stay in the conference hotel easily (and probably most could stay on the transfer floor). Some non-seekers might like to stay at the conference hotel (though many don’t like to), but seekers are most benefited by staying in the conference hotel, and most harmed by not staying in it because of the running around they must do. Sounds positive sum to us.

“One of the biggest risks facing you is that you will be forgotten. Make sure the interviewers know something unusual about you.”: Zero-sum. Or maybe positive-sum, I don’t know.

That would be positive sum. If you think, “but Decision Science News, one person being remembered means that another person will be forgotten”, we delight in declaring that memory is not like a stack of paper.  As one candidate’s probability of being remembered increases, the other candidates’ probabilities do not decrease in proportion. Memory, like much of the world (we are starting to realize as we write this), is not zero sum. And if more applicants are remembered, the better the chances that the market will arrive at good matches between schools and candidates, and that’s a good thing.

“It’s a good idea to hit a school with 2 packets, 3 if you suspect they’re a little disorganized.”: Negative-sum. I’m not saying this wouldn’t work–a couple of years ago, our department missed out on a top candidate because we literally lost his file. But it can’t be good to have duplicate letters flying around.

Or can it? When the job market fails, it can also be quite bad: couples can get stuck in different cities, people can take jobs then relocate a year later, etc. These events have environmental impact, too.

“Get your advisor / sponsor to write a cover letter encouraging people to meet with you at AMA.”: Zero-sum, I think.

This isn’t even really advice, more of a how-to. Candidates must have introductory letters if they want to be in the game at all. It’s like saying “if you want to get from Columbia to NYU, head downtown”.

“Don’t gossip.”: Negative-sum. I say this because Dan illustrates with a story where the gossiper provided him with useful information! So the gossip was probably helpful.

Kidding aside, I would guess that there are laws concerning rumors in financial markets because they find them to be bad for the larger system.

Given that in most real problems, one can futz with the reference classes, populations, probabilities and payoffs to arrive at whatever total one wishes, this blog wonders if zero sum analysis actually adds up.

THE MPG ILLUSION

In their carpooling conversations, friends of Decision Science News Rick Larrick and Jack Soll have a come up with poignant example of how information that is mathematically equivalent is psychologically different (to paraphrase Feynman). Their “miles per gallon illusion” has been passed by our editorial staff to policy makers and may someday, hopefully, change policy. It is definitely worth reading. Check out:

• The article in Science. (Psst: If you access the article from the link on this page, you don’t need a pricey subscription to Science to read the article.)
• The blog
• An interactive quiz
• And, of course, the summer blockbuster movie.

useR! CONFERENCE, AUGUST 12-14 2008, DORTMUND GERMANY

Impressive statistical computing types like Andrew Gelman, Gary King, and others will be presenting at this year’s useR! conference. Decision Science News might just have to hop over and check it out. The program looks great. Those interested in learning R might be interested in our Decision Science News R tutorials one and two.

About the Conference

useR! 2008, the R user conference, takes place at the Fakultät Statistik, Technische Universität Dortmund, Germany from 2008-08-12 to 2008-08-14. Pre-conference tutorials will take place on August 11.
The conference is organized by the Fakultät Statistik, Technische Universität Dortmund and the Austrian Association for Statistical Computing (AASC). It is funded by the R Foundation for Statistical Computing.

Following the successful useR! 2004, useR! 2006, and useR! 2007 conferences, the conference is focused on

1. R as the “lingua franca” of data analysis and statistical computing,
2. providing a platform for R users to discuss and exchange ideas how R can be used to do statistical computations, data analysis, visualization and exciting applications in various fields,
3. giving an overview of the new features of the rapidly evolving R project.

As for the predecessor conference, the program consists of two parts:

1. invited lectures discussing new R developments and exciting applications of R,
2. user-contributed presentations reflecting the wide range of fields in which R is used to analyze data.

A major goal of the useR! conference is to bring users from various fields together and provide a platform for discussion and exchange of ideas: both in the formal framework of presentations as well as in the informal part of the conference in Dortmund’s famous beer pubs and restaurants.

Prior to the conference, on 2008-08-11, there are tutorials offered at the conference site. Each tutorial has a length of 3 hours and takes place either in the morning or afternoon.

FIND THINGS FAST ON WINDOWS

A good theory of decision making needs to account for the fact that searching for information has real costs. For this reason, decision makers use different strategies when the information is conveniently laid out before them (as in the information-matrix paradigm) and when information is tucked away in memory or worse, the far-flung corners of the external world.

A surprisingly difficult place to find information is one’s own computer. While it takes only .07 seconds to search the entire internet for matters multinomial probit it takes Windows 5 minutes to do the same.

But not anymore. Cut to an email from the DSN editor to his co-workers:

Dear Colleagues,

I’m rarely one to recommend Microsoft software, but they’ve come out with an very good, free search tool that can find any file, email, contact, etc. on your computer in about 4 seconds. It’s about as easy as using Google and doesn’t bog down your computer.

Given that the old Windows search takes about 5 minutes and never finds what you want, this is wonderful. I’ve put it on 3 machines with no problems.

http://www.microsoft.com/windows/products/winfamily/desktopsearch/choose/windowssearch4.mspx?tab=Install%20It

Most of you are running XP and would thus want to click the link that says “For Windows XP (32-bit)”. The first time you run it, it takes a couple minutes to index your files. It helps to close Outlook so it can work on that info as well.

(Decision Science News does not wish to alienate Linux or MacOS users and hopes they already know about their options. Both can use the command-line “updatedb” (on Mac /usr/libexec/locate.updatedb) followed by “locate”. MacOSX users can benefit from Spotlight. Linux users on the Gnome desktop can put Beagle to work for them.)

Hat tip to Eric Johnson for spotlighting Spotlight.

Photo Credit: http://flickr.com/photos/marcus_hansson/87885327/

CALL FOR PAPERS: SJDM 2008 PRE-CONFERENCE. DEADLINE SEPT 1, 2008

Society for Judgment and Decision Making Preconference 2008: Using Human Nature to Improve Human Life. November 14, 2008. Gleacher Center, Chicago, IL.

The University of Chicago’s Center for Decision Research announces that it will host a preconference to this year’s SJDM Annual Meeting, featuring research on how basic knowledge about human nature (fundamental motives, habits, biases, limitations, etc.) can be used to improve individual and social welfare. The preconference will be held on November 14, 2008, and will take place at the Gleacher Center in downtown Chicago.

PRECONFERENCE THEME:

Research on human judgment and decision making has enriched our understanding of some of the basic features and limitations of human nature. People do not operate with perfect knowledge, unlimited mental capacity, complete self-control, or a perfect ability to appreciate the future as much as the present. These basic features of human nature do not make people inherently flawed, just inherently human. Attempts to improve human life require an understanding of these basic features of human nature in order to design policies and interventions that work within the people’s inherent constraints. Public policy has long been guided by a view of human nature provided by homo economicus, but public policy should also be informed by the psychological understanding of homo sapiens. Those designing organ donation policies, for instance, would do well to note that people are heavily influenced by the default option. Those designing savings programs would do well to note that people value future dollars much less than current dollars. And those designing weight loss programs would do well to note that people will eat whatever portion size is placed in front of them. Psychological research has a role to play in public policy debates and in designing social welfare interventions. This conference will provide a forum in which to present that research.

CALL FOR PAPERS:

The Center for Decision Research invites 1-page abstracts for oral presentations of research, which address any systematic human tendency, bias, limitation, or cognitive capacity that can be used to inform interventions or policy to improve human life. Discussion of specific intervention or policy implications is not required, but is encouraged. Faculty members, postdocs and graduate students, and anyone with interesting research to present are all eligible to submit. Submissions must be received by September 1, 2008, and should submitted with your registration for the conference through our website: http://www.chicagocdr.org/sjdm_precon.html

REGISTRATION:

Attendance for the preconference is limited. To reserve a space for yourself, please visit our conference website: http://www.chicagocdr.org/sjdm_precon.html

PROGRAM:

The preconference will last a full business day, organized in two sessions which will feature Cornell University’s Brian Wansink (discussing his work related to obesity and health) and Princeton’s Eldar Shafir (discussing his work on poverty) alongside the other presenters.

Photo Credit http://www.flickr.com/photos/esspea/288035510/

SOFTWARE TO DEAL WITH ULTIMATELY UNDESRIABLE INTERTEMPORAL PREFERENCE SHIFTS

Ever find yourself frittering away the day responding to email after email? Ever think that if you’d just spent 8 hours working on that project, you’d be done and still have time to answer those emails in front of the TV later that night? Sure, we all have.

Why we simply don’t do the hard stuff first is a fascinating question in its own right. I mean, if we’re going to be happier at the end of the day having ignored the emails, why don’t we learn to ignore them? It’s too much to get into here, but see the psychological literature on intertemporal choice and the Don’t Delay blog if this interests you.

The good news is that the always-innovating Google is here to help with their experimental “Take a Break” feature in Gmail. When clicked, it prevents you from checking your email for 15 minutes, telling you do something more productive instead.

To use it, you’ll need to manually activate “Gmail Labs” inside Gmail. See the Gmail blog or if you’re impatient, try Settings -> Labs from Gmail. Right now, it’s only enabled in the US and UK.

Other tools to try if you can’t get down to work at work:

* Temptation Blocker: a Windows program to prevent you from using any other program (especially good to prevent you from opening your Email client or Web browser).
http://sourceforge.net/projects/temptblocker/

* Time Tracker: An extension to the FireFox browser that tracks how much time you waste on various sites.
https://addons.mozilla.org/en-US/firefox/addon/1887

FIREFOX USERS CAN HELP SET A WORLD RECORD

** NOTE: Please wait until the release time to download: 10 AM LA, 1PM New York, 6PM London, 7PM Paris **

What do browsers have to do with decision making? They are an excellent illustration of the power of defaults. The default home page within a browser is kept by vast numbers of users. The operating system’s default browser has, historically, has been adopted by most people. For this reason, the default browser and its settings exert an enormous influence over Web traffic, which translates rather directly into advertising revenue. And we’re not talking peanuts: Google earned $20 billion last year.

However, when a browser gets really good, it can overcome the odds and achieve widespread usage despite not being the default. FireFox is such a browser and for this reason is the official browser of Decision Science News.

Today, June 17th, 2008, marks the historic release of FireFox version 3. It can be downloaded for from the link at the bottom of this post. The source code is also free, if you’re a nerd and would like to modify it to suit your needs.

The good people at Mozilla are trying to set the world record for the most software downloads in a 24 hour period. If you like FireFox, today is your chance to help set that record, and download the new FireFox 3 today.

http://www.spreadfirefox.com/en-US/worldrecord/

24th ANNUAL INTERNATIONAL MEETING OF THE BRUNSWIK SOCIETY, NOV 13-14, 2008

Call for Papers and Participation

Dear friends and colleagues,

The 24th Annual International Meeting of the Brunswik Society will be held on Thursday and Friday, November 13-14, 2008 in Chicago, Illinois, at the Hilton Chicago. The program begins at 12:00 noon on Thursday afternoon, and ends at 6:00 Friday afternoon. We invite papers and/or panel discussion proposals on any theoretical or empirical/applied topic directly related to Egon Brunswik’s philosophy and paradigm. Please send a brief abstract (100 words), and indicate whether the paper/discussion is theoretical or empirical, to Jim Holzworth by Friday, July 18th. Kindly respect this submission due date. The organizing committee is: Jim Holzworth Jim.Holzworth@uconn.edu, Mandeep Dhami mkd25@cam.ac.uk, and Elise Weaver elise_weaver@yahoo.com. The meeting is held concurrently with the Psychonomic Society Annual Meeting and just before the Judgment and Decision Society meeting. More details about the 2008 meeting, including registration instructions, will be posted on the Brunswik Society website, at http://brunswik.org.

TEST YOUR SOCCER PREDICTION SKILLS

Stefan Herzog over in Basel lets us know about a short online study (15 – 20 minutes) on how people predict outcomes in the context of football (soccer). Anybody can participate; this study is explicitly not just for people who are interested or an expert in football.

You can optionally request (a) feedback on your prediction strategy and (b) additional information about this study (once it is completed).

This study is non-commercially oriented, that is, its data is solely used for scientific purposes and is treated confidentially.

Please visit: http://phpserver.psycho.unibas.ch/em2008/

Thank you very much for participating!

Photo credit: http://www.flickr.com/photos/76579169@N00/178821720/

UPDATE
In a bold move, the authors have decided to publish their predictions here on Decision Science News so that nobody can accuse them of changing their model after the matches begin. For further evidence, the results have been archived at The Internet Archive. Here they are:

game group team1 team2 rec1 rec2 recrank1 recrank2 rec_prediction
1 A SUI CZE 0.25 0.26 9 8 CZE
2 A POR TUR 0.41 0.15 3 13 POR
3 B AUT CRO 0.15 0.24 12 10 CRO
4 B GER POL 0.49 0.14 1 14 GER
5 C ROU FRA 0.12 0.4 15 4 FRA
6 C NED ITA 0.35 0.43 5 2 ITA
7 D ESP RUS 0.35 0.12 6 16 ESP
8 D GRE SWE 0.17 0.31 11 7 SWE
9 A CZE POR 0.26 0.41 8 3 POR
10 A SUI TUR 0.25 0.15 9 13 SUI
11 B CRO GER 0.24 0.49 10 1 GER
12 B AUT POL 0.15 0.14 12 14 AUT
13 C ITA ROU 0.43 0.12 2 15 ITA
14 C NED FRA 0.35 0.4 5 4 FRA
15 D SWE ESP 0.31 0.35 7 6 ESP
16 D GRE RUS 0.17 0.12 11 16 GRE
17 A SUI POR 0.25 0.41 9 3 POR
18 A TUR CZE 0.15 0.26 13 8 CZE
19 B POL CRO 0.14 0.24 14 10 CRO
20 B AUT GER 0.15 0.49 12 1 GER
21 C NED ROU 0.35 0.12 5 15 NED
22 C FRA ITA 0.4 0.43 4 2 ITA
23 D GRE ESP 0.17 0.35 11 6 ESP
24 D RUS SWE 0.12 0.31 16 7 SWE
country group rec recrank
GER B 0.492 1
ITA C 0.432 2
POR A 0.409 3
FRA C 0.4 4
NED C 0.354 5
ESP D 0.347 6
SWE D 0.307 7
CZE A 0.26 8
SUI A 0.246 9
CRO B 0.24 10
GRE D 0.167 11
AUT B 0.153 12
TUR A 0.146 13
POL B 0.135 14
ROU C 0.125 15
RUS D 0.116 16