How to read Corona Maps

Let us generate a sample map of Connecticut. There are three values used to generate the maps (We will start with values from July 26, but you can see how the actual values are collected via the code on GitHub). Also note the abbreviation for each county: (F)airfield, (H)artford, (L)itchfield, (M)iddlesex, (N)ew (H)aven, (N)ew (L)ondon, (T)olland, (W)indham

LW: Total number of new cases in the last week. Obtained by taking total number of cases today minus total number of cases 7 days ago.

WBL: Total number of new cases in the week before last. Obtained by taking total number of cases 7 days ago minus total number of cases 14 days ago.

MON: Total number of new cases in the last month. Obtained by taking total number of cases today minus total number of cases 28 days ago.

	F	H	L	M	NH	NL	T	W
LW	352	294	37	8	151	15	27	7
WBL	163	154	13	22	201	25	9	19
MON	815	782	78	78	609	121	58	59

Cases are increasing in the north and west of the state, while they are decreasing in the south and east. Notice that the map has one frame and it gives a rate for all counties which have more than 0, but fewer than 1 cases per 1000 residents in the past month. Ideally, your state is like this. On the "more than 0" frame, red areas can serve as an early warning, but may be noise in less populated counties.

Let us pretend that two weeks pass. Counties in the west will add more cases but at a slower rate and in the east the new case count will continue to drop.

	F	H	L	M	NH	NL	T	W
LW	400	300	60	10	200	10	15	5
WBL	300	200	40	15	200	10	15	10
MON	1215	948	150	55	752	60	66	41

As we can see, our problem counties, Fairfield and Hartford, are a lighter shade of orange now, so the virus is spreading more slowly, but it is more widespread in the counties which appear in later frames, therefore it is more concerning. It is better to be a red color in an earlier frame than orange in a later frame. Let us simulate the last two weeks again, but this time, Fairfield County will add 1200 in the last week and Windham County will only have added 1.

Now you can see a difference in both how far and fast the virus has spread in an area. Note, Windham went from green to blue on a difference of 4 cases in the last week. So, when you see extreme colors in the first frame, try not to draw broad conclusions. However, if the county is fairly populated or starts appearing in later frames, "the redder, the deader."