“It’s the Phone, Stupid: Mobiles and Murder”, 2019-10 ():
US homicide rates fell sharply in the early 1990s, a decade that also saw the mainstreaming of cell phones—a concurrence that may be more than a coincidence, we propose. Cell phones may have undercut turf-based street dealing, thus undermining drug-dealing profits of street gangs, entities known to engage in violent crime.
Studying county-level data for the years 1970–39200915ya we find that:
the expansion of cellular phone service (as proxied by antenna-structure density) lowered homicide rates in the 1990s. Furthermore, effects were concentrated in urban counties; among Black or Hispanic males; and more gang/drug-associated homicides.
…They estimate that the diffusion of phones could explain 19–29% of the decline in homicides seen 1990–10200024ya.
“The cellphones changed how drugs were dealt”, Edlund told me. In the 1980s, turf-based drug sales generated violence as gangs attacked and defended territory, and also allowed those who controlled the block to keep profits high. The cellphone broke the link, the paper claims, between turf and selling drugs. “It’s not that people don’t sell or do drugs anymore”, Edlund explained to me, “but the relationship between that and violence is different.”
…Edlund and Machado are not the first to suggest that phones could have played a role in the decline. Among others, the criminologists Erin Orrick and Alex Piquero were able to show that property crime fell as cellphone-ownership rates climbed. The first paper on the cellphone-crime link suggested that phones were an “underappreciated” crime deterrent, as mobile communications allow illegal behavior to be reported more easily and quickly.
…Several people whom I asked to review Edlund and Machado’s paper thought the size of the effect was probably too large. “It is not inconceivable that their theory was a contributing factor, but 20–30% seems like a lot”, said Inimai Chettiar, the director of the Brennan Center’s Justice Program, which did a large-scale review of the crime decline several years ago. For the period 1990–9199925ya, the Brennan Center found that all the following factors combined explained only about a quarter of the drop: increased incarceration, increased police numbers, aging population, growth in income, decreased alcohol consumption, and unemployment. They also concluded that the decrease in environmental lead exposure and crack use and the increase in abortions “possibly” had some effect.
The University of Leeds criminologist Graham Farrell, who is closely associated with the hypothesis that better security technology is the primary cause of the crime decline, also took issue with some of the paper’s data analysis. “At first glance, it seems to be that antenna [density] increased mostly after homicide already declined”, he wrote to me in an email.
The data that the economists presented don’t match the chronology of the decline of homicides, especially considering that their proxy variable—how many antennas were up—would almost certainly precede cellphone usage by some period of time. The timing, he said, is “not even close.”
So many of the theories have what Farrell called “initial plausibility”, and data can be marshaled to support them. But when critics reanalyze the discovery, they find holes. The data don’t hold up across time, across cities, or across countries. The problem is analogous to something like dark energy in physics—a sort of unexplained, unseen material that confounds the calculations of different branches of the social sciences.
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