Crimewave's end ...

Phil Henshaw  NY NY  10/22/05  02/23/08 12/29/09

The question is, what happened?

On Aug. 7 2005 I posted "A Quick Study" of this same history of murder rates in New York State. The relatively sudden and very final end to 'the great crimewave' that started with the ghetto uprisings in the 60's, is a dramatic example of dynamic cultural change.  It began with a very public change of heart, that inner-city black youth, primarily, used their new freedoms to reject society, and after many tumultuous years ended in an almost completely silent, but equally dramatic change of heart to end it.  

(click on image for source data site)

12/29/09The strong indicator that a cultural change occurred is the regular decay curve marking a shift from high and variable murder rates, to low and and completely flat rates, the collapse of the murder rate and beginning of a distinct period of quiet, that has now continued through 2009.  That marks a clear 'change of state', and not the kind of thing caused by police pressure in a wild town like New York.   When you look closely at the data for each borough (below) it appears that in each one there was a specific intense crime spree that was "over the top" and tipped the balance causing each neighborhood to somewhat abruptly reject the virulent crime culture that raged in their midst at the time, and simply stop giving their sons and daughters to it.   That's a little speculative, yes, but supported by many kinds of indications, including that the drop in crime rates that followed was as precipitous and permanent.  It was as if at that peak moment the drug warriors the police kept sweeping off the streets endlessly, just abruptly stopped being replaced.   That's the meaning of a rapid decay curve here, a distinct sudden absence of resupply.   pfh

02/23/08 Another 'sneaky' indication, is, well, that it was so sneaky.    No one noticed it happening.  There was even a notable mayor who came into office three years after the collapse began and claimed credit for the whole change of character in the city.    There's really no outside factor yet identified, though, that matches the timing, or finality, of the change.   There's no outside cause to explain the more or less sudden relief from a long persistent culture of violence which every possible effort was targeting to end for a great many years.  In the various news accounts and studies I've read one of the odd consistencies is that no one seems to have asked the people involved what they thought happened.   So I went out and did a number of  interviews on the streets of Harlem and the Bronx to see if people remembered what it was.   There may be other scientists who have done so, but I have not read about it. ( The study was not meant to be exhaustive, and but to explore my method with a minimal amount of effort, to see if some better questions would come out of it.

It certainly is only one data set, but does expose an unheard from inside point of view. I just handed out a blow-up of the curve asking "were you around here in the 90's", and "do you remember what happened here", leading people as little as I could until they offered something they remembered happening that they associated with it. The text file contains brief notes reflecting 50 good conversations with people, four audio file links, and my compilation of the reasons people gave. It's always great to get out and talk to people, and one rarely has something to ask them that is so central to their own lives and mysterious at the same time. Judge for yourself. Naturally I described what I could make sense of, introducing some of my own perceptions in the process, but I tried to just record the story tellers.

Often the picture you see in a data set depends on how you aggregate the data.   Among the questions that can't be answered from the Statewide data in the curve above, from a systems point of view, is whether every city in the state had the same trend as the aggregate (all of them together), and particularly whether the turning points for each city were at the same time, or in sequence.   That would suggest or rule out several paths of causation.   When I got more detailed data it came in the form of murder rates for each of the 75 precincts in NY City, and did not include those for the upstate cities, so that line of inquiry couldn't be followed.   I then spent a lot of unproductive time looking at the citywide distribution of rates of all the precincts, and found all the patterns randomly scattered,... until I tried grouping the precincts by borough.   Each borough had distinctly different behavior that was very readily visible and very consistent with my own understanding of their familiar
social character.

One might also ask, did I bias my findings by possibly asking the questions in a way that determined the answer I got?  People do indeed commonly find what they're looking for because of that. Well, I found something like I was looking for, but I tried to be careful about that. I did push people to recall what was going on inside the their culture, asking about events without names, signs of change easily forgotten. From my own experience of living on West 96th street at the time I thought the turnaround might have had something to do with those amazing memorial murals that the 'wild style' graffiti artists made on handball court walls all over town for the families and friends of the victims of the street.   I never guessed that when I asked people about that specifically they would remember but not give it much importance.  It was such a dramatic and short term art action phenomenon (nicely recorded in "R.I.P. Memorial Wall Art") occurring seemingly just at the moment of the break.   Now I think it was just one of a great many 'mirrors' of what was happening that a great many caring people and organizations began holding up for the people of the 'hoods'  to see themselves in.   It's a new perception actually, coming about three years after my interviews, about what the common element in a number of the provocative comments.   That a huge sudden change in our local culture of such enormous importance would go essentially unnoticed is still the most amazing thing.   It really took work to get people to remember what happened at all!

In studying the borough murder rates another simple evidence of a culture wide event to end the crimewave is that all the boroughs show the same timing and kind of simple murder rate decay curve after their crack epidemic peaks.   There are a number of puzzling things about the different times of peak murder rates.  The Manhattan murder rate peak was were 10 years before the peak murder rates of the crack epidemic, for one.  I haven't pursued the social change that meant violence in Manhattan did not increase with the crack epidemic as it did elsewhere.  

(click on images for larger versions)


Derivative reconstruction is a time line smoothing routine that effectively assumes that local fluctuations are superimposed on larger ones, and 'looks for' a smooth way to thread through local fluctuation.  When the borough murder rate curves are smoothed using it, it is then possible to estimate the exact times when the inflection points of the underlying processes occurred.  It's an assumption that bears validation.

The inflection points of a transient social event seems reasonable to interpret in this case as the points at which the community response to the intrusion began to stabilize..   Part of the puzzle here is why did each higher crime borough show a later time of effective response (with the lowest crime borough, SI, seeming to be the first to effectively respond to the intrusion, as well as the one to continue its response the longest).


Other figures:
US murder rates since 1900 w/ NY & other States
Queens & S.I. Murder Rates enlarged w/ DR
NYC Precinct Murder Rates
Power Point of all the large data curves

literature review intentionally limited to give it a 'blank slate' for open inquiry
see also the inside views:
"Wild Cowboys" Jackall 1997 Harvard Univ. Press
"R.I.P. Memorial Wall Art" Cooper & Sciorra, Henry Hot and Co.

Physics of Happening