Via The Conversation, an article by Richard Casey Sadler of Michigan State University: How ZIP codes nearly masked the lead problem in Flint. Excerpt:
I write this as we approach the first anniversary of my involvement in the Flint Water Crisis, an ongoing catastrophe and basic failure of government accountability that will soon approach three years.
On Sept. 25, 2015, I received a call from my colleague – the now-renowned Dr. Mona Hanna-Attisha – asking if I could run some basic spatial analysis of blood lead data collected from area pediatric clinics. I had heard rumblings that blood lead levels were on the rise in Flint but that state officials were pushing back against her findings.
My job was to examine blood lead data from our local Hurley Children’s Hospital in Flint for spatial patterns, or neighborhood-level clusters of elevated levels, so we could quash the doubts of state officials and confirm our concerns. Unbeknownst to me, this research project would ultimately help blow the lid off the water crisis, vindicating months of activism and outcry by dedicated Flint residents.
As I ran the addresses through a precise parcel-level geocoding process and visually inspected individual blood lead levels, I was immediately struck by the disparity in the spatial pattern. It was obvious Flint children had become far more likely than out-county children to experience elevated blood lead when compared to two years prior.
How had the state so blatantly and callously disregarded such information? To me – a geographer trained extensively in geographic information science, or computer mapping – the answer was obvious upon hearing their unit of analysis: the ZIP code.
Their ZIP code data included people who appeared to live in Flint and receive Flint water but actually didn’t, making the data much less accurate than it appeared.
ZIP codes – the bane of my existence as a geographer. They confused my childhood friends into believing they lived in an entirely different city. They add cachet to parts of our communities (think 90210) while generating skepticism toward others relegated to less sexy ZIP codes.
Dr. Tony Grubesic, an Arizona State University professor, has called them “one of the quirkier ‘geographies’ in the world.” Dr. Nancy Krieger, a Harvard University professor, and colleagues have called out their unacceptability for small-area analyses.
If I were to have simply summarized blood lead statistics by ZIP code, the pattern would not have been striking. The state, having done just this, incorrectly concluded that the change in water source had no discernible effect on Flint children.