Idiot science? Urban vegetation decreases violent crime but not theft!

Correlation and causation again! Correlation does not necessarily mean causation and even real causation may not give any correlation.

The authors are from the Department of Geography and Urban Studies, Temple University, United States. And they get paid for this?

Does vegetation encourage or suppress urban crime? Evidence from Philadelphia, PA, Mary K. Wolfe and Jeremy Mennis, Landscape and Urban Planning, Volume 108, Issues 2–4, November–December 2012, Pages 112–122, http://dx.doi.org/10.1016/j.landurbplan.2012.08.006

(emphasis added)

AbstractThere is longstanding belief that vegetation encourages crime as it can conceal criminal activity. Other studies, however, have shown that urban residential areas with well-maintained vegetation experience lower rates of certain crime types due to increased surveillance in vegetated spaces as well as the therapeutic effects ascribed to vegetated landscapes. The present research analyzes the association of vegetation with crime in a case study of Philadelphia, Pennsylvania. We examine rates of assaults, robberies, burglaries, and thefts in relation to remotely sensed vegetation abundance at the Census tract level. We employ choropleth mapping, correlation, ordinary least squares regression, and spatial econometric modeling to examine the influence of vegetation on various crime types while controlling for tract-level socioeconomic indicators. Results indicate that vegetation abundance is significantly associated with lower rates of assault, robbery, and burglary, but not theft. This research has implications for urban planning policy, especially as cities are moving towards ‘green’ growth plans and must look to incorporate sustainable methods of crime prevention into city planning.

And Discover Magazine comments (comments?)

The explanation, the authors say, is twofold: One, green spaces encourage people to spend more time socially outdoors, which discourages crime. It’s especially helpful for crime control when young and old people mix together in public places. And two, the presence of plants has a therapeutic effect. Vegetation decreases mental fatigue and its associated symptoms, such as irritability and decreased impulse control, both considered to be precursors to violence.

This “plant therapy” mechanism is bolstered by the Philadelphia findings. The most violent of the crimes studied, aggravated assault, was most strongly correlated with a neighborhood’s degree of greenness, while the least violent crime, theft, showed no association. This could indicate that it’s a violent mentality itself that green spaces are discouraging.

That hypothesis needs further study.

And that last line is the giveaway.

No, every idiot hypothesis does not need further study! 

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