Free The Numbers Behind NUMB3RS by Keith Devlin Page B

arrests were made on that occasion. But the authorities did obtain a good picture of the conference call pattern associated with that kind of activity, and it is possible that, based on the findings of the study, the telephone company subsequently trained one of its own neural networks to look for similar patterns as they occur , to try to catch the perpetrators in the act. (This is the kind of thing that companies tend to keep secret, of course.)
    Battles such as this never end. People with criminal intent will continue to look for ways to defraud the telecommunications companies. Data mining is the principal weapon the companies have in their arsenal to keep abreast of their adversaries.
    MORE DATA MINING IN NUMB3RS
    Given the widespread use of data-mining techniques in many areas of modern life, including crime detection and prevention, it is hardly surprising that Charlie mentions it in many episodes of NUMB3RS . For example, in the episode “Convergence,” broadcast on November 11, 2005, a chain of robberies at upscale Los Angeles homes takes a more sinister turn when one of the homeowners is murdered. The robbers seem to have a considerable amount of inside information about the valuable items in the houses they rob and the detailed movements of the homeowners. Yet the target homes seem to have nothing in common, and certainly nothing that points to a source for the information the crooks are clearly getting. Charlie uses a data-mining program he wrote to look for patterns among all robberies in the area over the six-month period of the home burglaries, and eventually comes up with a series of car thefts that look as though they could be the work of the same gang, which leads to their capture.
    Further Reading
    Colleen McCue, Data Mining and Predictive Analysis , Butterworth-Heinemann (2007).
    Jesus Mena, Investigative Data Mining for Security and Criminal Detection , Butterworth-Heinemann (2003).

CHAPTER 4
When Does the Writing First Appear on the Wall?
    Changepoint Detection
    THE BASEBALL NUMBERS GENIUS
    In a third-season NUMB3RS episode entitled “Hardball,” an aging baseball player, trying to make a comeback after several lackluster years in the minors, dies during on-field training. When the coach opens the dead player’s locker, he finds a stash of needles and vials of steroids, and at once contacts the police. The coroner’s investigation shows that the player suffered a brain hemorrhage resulting from a massive overdose of steroids, which he had started using to enhance his prospects of a return to the major league. But this was no accidental overdose. The drug in his locker was thirty times more powerful than the normal dosage, and had to have been prepared specially. The player had been murdered.
    When Don is assigned to the case, he discovers some e-mails on the player’s laptop from an unknown person who claimed to know that he was taking performance-enhancing drugs and threatened to inform the authorities. It looks like a case of blackmail. What is unusual is the proof that the unknown extortionist claimed to have. The e-mails have an attachment—a page of mathematical formulas that, the e-mailer claimed, showed exactly when in his professional career the player had started taking steroids.
    Clearly, this was another case where Don would need the help of his younger brother. Charlie recognizes at once what the mathematics is about. “That’s advanced statistical baseball analysis,” he blurts out.
    â€œRight, sabermetrics,” replies Don, giving the accepted technical term for the use of statistics to analyze baseball performance.
    The term “sabermetrics” is derived from the acronym SABR, which stands for the Society for American Baseball Research, and was coined by baseball statistics pioneer Bill James, one of the most enthusiastic proponents of using numbers to analyze the game.
    Charlie also observes that whoever produced the formulas had