|Georgia Department of Public Health maps|
First, he noted, the the maps' color key is all blue except for the very worst counties, which are red. That may suggest that they are the only ones in serious trouble. A graduated color scheme with shades all the same color would show the data more clearly, he and others in the discussion argue. (Or one with a logical color progression from blue to red, implying cold to hot.)
He also notes that the values for each color change because it's set up in quintiles, five equivalent segments of the dataset. The numbers that those quintiles represent change over time as case numbers change. For example, in the July 2 map, red counties had between 2,961 and 4,661 cases per 100,000 residents. But on the July 17 map, red counties have between 3,769 and 5,165 cases per 100,000.
The state's website says the charts are "meant to aid understanding whether the outbreak is growing, leveling off, or declining and can help to guide the covid-19 response." Georgia Person argued that, by not formatting the maps to show the increase in cases, the state is abdicating its responsibility to highlight important information, whether it was done by poor design or with malicious intent.
Rural areas of Georgia have been particularly hard-hit, especially counties with majority African-American populations. Rural African Americans are more vulnerable to dying from covid-19.