Crime mining: Hidden history emerges from court data – 25 June 2014 – Control – New Scientist

Hidden history emerges from [#mining] court data Diverging descriptions of types of #crime likened to genetic drift

Back to the future
Jennifer Ouellette
Available online 28 June 2014


Instead, he turned to information theory, invented by Claude Shannon
in the 1940s. DeDeo’s aim was to reveal gradual changes in the way
crimes were spoken about. He split all the trials into two categories
– trials for violent crimes like murder or assault and trials for
non-violent crimes like pickpocketing or fraud – and then he looked at
the actual words that people used in the courtroom. Information theory
lets you quantify the amount of information given by a word in a
specific context. Using a measure known as Jensen-Shannon divergence,
a word picked at random from the transcript of a trial can be given a
score based on how useful it is for predicting the type of the trial.

So, for example, if you walked into the Old Bailey during Hall’s trial
and heard the word "murdered" uttered in court, how much information
about the type of trial underway would that single word convey? In the
early years of the period they looked at, most crimes involved some
level of violence. "There might be bloodshed, or an eye gouged out,
but the real crime is someone’s wallet got stolen," DeDeo says. "The
casual everyday violence of the past is remarkable."

Slowly, however, that changed. By the 1880s, the team found that the
majority of violent language was reserved for talking about crimes
like assault, murder or rape. So you could walk into the courtroom,
hear words like "murdered", "hit," "knife" and "struggled" – all words
from Martin’s testimony in 1801 – and be confident that you were
witnessing a trial for a violent crime rather than a trial for theft.

The analysis reveals a story of the gradual criminalisation of
violence. This is not necessarily evidence that we have become less
violent – as Steven Pinker argues, based on statistics for violent
crime, in his book The Better Angels of Our Nature. Rather, it is a
story of the state gaining a monopoly on violence and controlling its
occurrence among the public. "What is deemed criminal has changed,"
says Hitchcock.

DeDeo likens the shift to genetic drift. If you took two herds of
goats and isolated each for centuries, the herds would gradually
evolve into separate species. Similarly, he sees Old Bailey cases as
populations of violent and non-violent trials. Over time the two types
"speciate" and become distinct from one another (see chart). "In 1760,
the patterns of language used in both kinds of trial are almost
exactly identical," he says. "Over the next 150 years they diverge."

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