When my father was called up for the Army in October 1944 for World War II, we moved to Iowa where he had been born, to be near family while he was gone. I remember the humid nights, the chiggers that bit if you rolled on the lawn, and the beautiful snows until the coal soot turned the snowdrifts black.
And I remember the 'family farm' halfway between Jewell and Webster City. No running water, an outhouse 'restroom' and the steep cold stairs to my attic bedroom in the crisp autumn days. Not yet four years old, I collected eggs from the chicken coop, fed the pigs 'corn on the bone' not knowing what a 'cob' was, and milked the two daily cows we had with my great-uncle Fred and his son "Buddy".
The road to 'town' was newly paved, and you could put your ear to the ground and listen for an approaching car--one came by nearly every hour.
I went back with my wife Jenny fifty-five years later, and I was surprised by how close the barn was to the house--back then, it seemed a long ways away, but at three, I had shorter legs.
All of these memories came flooding back when I saw the headline "COVID-19 surge moves to Midwest" on the bulletin from the Center for Infectious Disease Research at the University of Minnesota https://www.cidrap.umn.edu/news-perspective/2020/08/covid-19-surge-moves-midwest-young-people-fuel-us-case-rise
"Many states initially spared from the COVID-19 pandemic is March, April, and May, are now reporting increasing transmission rates in non-metropolitan counties fueled by community spread. According to the Wall Street Journal, ... the weekly change in COVID-19 cases has been higher in rural regions compared to metro areas, and outbreaks are linked to social events, rather than workplace exposure or congregate living situations."
Since I had just done an analysis of eight counties in Iowa, aggregated around the Webster City and Jewell areas, and had found substantially what they were now reporting, I felt both vindicated for what our Dashboard can help discover, and satisfied that I was able to detect this before 'reading about it'.
So, I thought it might be worth sharing a couple of those points herein:
A. Absolute numbers are relatively meaningless when it comes to Covid. Of course, Los Angeles County is very high, as was New York City. There are more people there--re Los Angeles County, which is composed of a hundred towns and cities, the county has more people than all but six other states besides California.
B. Per capita numbers are not usually reported, or appreciated, but these in fact measure the relative impact on people in YOUR community by comparison with any other community.
C. Time-scales matter. Are we talking rate of infection per day, per week, per month? This obviously changes the odds, sometimes dramatically.
D. Choropleths (geo-spatial maps) are being increasingly used, but are not well understood. The 'cutting points' that determine color shadings are crucially important for conveying the 'right message'--who'd have thought that, especially if you're not practiced in reading these?
So, herewith some Iowa graphs, comparing two time-intervals (the first five months of the pandemic in America, with six weeks from mid-June to the end of July), call them Group A and Group B
The key to note in these graphs is that for three of the four, it appears that there is little change, or else that things are getting better (albeit that the time-scales are not equivalent). But SIGNIFICANTLY in my view, the third set--PER CAPITA CASES--shows that it has actually gotten WORSE recently, meaning it is much more widespread even with fewer cases.
1. Absolute CONFIRMED CASE numbers--Group A is 20% higher than Group B
2. Absolute DEATHS numbers--Group A is 208% higher than Group B
3. Cases Per Capita--Group A has 18 'very low' counties; Group B has only 3
4. DEATHS per capita -Group A has 6 VERY HOT and 13 HOT spots
Group B had NO VERY HOT, and only 5 HOT spots
SO, WHAT CAN WE LEARN FROM THIS that might be surprising?
The most important lesson for me was that Figure 3 is NOT INTUITIVE. Number of cases is down 20%, but the spread is MUCH WIDER. This phenomenon does not show up in the tabular data (I looked repeatedly at it), and it certainly doesn't show up in Figures 1, 2, and 4.
What is indeed going on here? The answer is a bit complicated. Yes, the urban areas (and in Iowa, there are not many) were one locus of the Case reduction. The other is that localized 'hotspots' happened in the Group A period to a much higher degree than in Group B--these were feedlots, food processing plants, nursing homes, and prisons. Yes, the Webster county prison outbreak (113 prisoners and 15 staff) was in the Group B time, but almost all of the Group B transmissions were 'community spread'.
Iowa has 99 counties, and 3.17 million residents. 8 counties account for 50% of the population, and within those 8 counties, cities account for 63% of their population. So, 8 counties with roughly 190,000 residents on average, and 91 counties with 17,000 residents on average is what the state demographics look like.
The top 2 counties (Polk, with Des Moines; Woodbury, with Sioux City) were 8,182 cases in Group A, but only 4,881 in Group B. That is 3,301 case reductions of the 3,594 total.
CONCLUSION: Choropleths can be quite revealing, especially for counter-intuitive matters. As in so many other avenues of life, the details are crucial, and tools that help us see them are indeed valuable for analysis and perspective.
Your thoughts?