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The good news is today's US Confirmed Case Count grew by only 41%, which is less than yesterday's massive 76% increase.

The bad news is I still suck as a virus forecaster, but anyone who shoots knows that if you're pulling left, all you need to do is make an adjustment. It seems that the US growth rate pattern since March 14 is more correlated with that of Hubei starting on Jan 24 vs Jan 30 (which is my starting point). However, I'm sticking to my bad forecast for now. Besides, you never know...the Red Sox beat the Yankees after trailing by three games to win the Pennant a few years ago.

I've introduced a new column, of % daily growth in confirmed US Cases. I think this helps flesh out where we were, and where we're going...and how bad I'm failing. Rock on.

Date	Forecast Cases: Hubei Pattern	Forecast Percent Growth	Actual Cases	% Daily Growth in Actual Cases	% diff: Actual-Forecast Cases	Logistic Forecast: 1/(1+exp(-( -3.2392+0.1988day of the epidemic)))41500	% diff: Actual-Logistic Forecast Cases
3/14/20	2,999	38.0%	2717	25%	-9%	3,315	-18%
3/15/20	3,552	18.4%	3478	28%	-2%	3,974	-12%
3/16/20	4,376	23.2%	4645	34%	6%	4,748	-2%
3/17/20	6,837	56.3%	6362	37%	-7%	5,650	13%
3/18/20	8,271	21.0%	7769	22%	-6%	6,693	16%
3/19/20	10,202	23.3%	13680	76%	34%	7,885	73%
3/20/20	12,029	17.9%	19285	41%	60%	9,233	109%
3/21/20	13,526	12.4%	.	.	.	10,739	.
3/22/20	15,264	12.8%	.	.	.	12,395	.
3/23/20	16,577	8.6%	.	.	.	14,189	.
3/24/20	18,125	9.3%	.	.	.	16,099	.
3/25/20	19,408	7.1%	.	.	.	18,096	.
3/26/20	20,410	5.2%	.	.	.	20,144	.
3/27/20	20,410	0.0%	.	.	.	22,204	.
3/28/20	29,488	44.5%	.	.	.	24,236	.
3/29/20	33,280	12.9%	.	.	.	26,201	.
3/30/20	34,408	3.4%	.	.	.	28,066	.
3/31/20	35,590	3.4%	.	.	.	29,806	.
4/1/20	36,696	3.1%	.	.	.	31,401	.
4/2/20	37,731	2.8%	.	.	.	32,842	.
4/3/20	37,945	0.6%	.	.	.	34,125	.
4/4/20	38,196	0.7%	.	.	.	35,255	.
4/5/20	38,331	0.4%	.	.	.	36,238	.
4/6/20	39,201	2.3%	.	.	.	37,086	.
4/7/20	39,201	0.0%	.	.	.	37,811	.
4/8/20	39,325	0.3%	.	.	.	38,427	.
4/9/20	39,630	0.8%	.	.	.	38,947	.
4/10/20	39,875	0.6%	.	.	.	39,384	.
4/11/20	40,125	0.6%	.	.	.	39,749	.
4/12/20	40,320	0.5%	.	.	.	40,054	.
4/13/20	40,579	0.6%	.	.	.	40,307	.
4/14/20	40,927	0.9%	.	.	.	40,517	.
4/15/20	41,047	0.3%	.	.	.	40,691	.

I think your forecast is good. Lots of unknowns, and initial testing is going to throw it off as it was starting from behind the curve. So deviations are to be expected.

I am fascinated by your analysis, even if the last 2 days are not fitting well. So I set up my own Excel doc with your equation.

QUESTIONS:

1) How did you arrive at the asymptotic value of 41,500? I thought we were solving for the max cases ... but now I realize that assumption came from a priori reasoning.

2) Obviously the epidemic hit the U.S. earlier than your current assumption, which places patient “Zero” around March 10th ... whereas there were at least 70 known cased by about March 2nd or so. So I’m thinking March 14 should be more like DAY 15 in the growth equation.

3) Can you give me some insight where the other 2 parameters in the exponent came from?

4) I get a better fit to the data, especially today’s totals, using March 14th as day 15, setting the MAX CASES=500,000; resetting your .1988 factor to .2754311; and resetting your 3.2392 factor to 9.0.

Even so, this assumes there was a degree of under-testing until the last 2 days.

NOTES:
500,000 confirmed cases (if that were the number) would certainly not overwhelm the health system, and would probably result in just few thousand deaths, allowing POTUS to declare victory.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It is conceivable the Trillion-Dollar BAILOUT CHECKS ALONE could cost about $1 billion per death.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Someday we will truly understand the growth function of this virus, and be able to assess the magnitude of the (over)reaction versus what we could have legitimately faced with normal safeguards like washing hands and quarantining actual cases.

Despite my forecasts continuing to be way off, the rate of growth in the US slowed for the second day in a row. It's also worth noting that NY accounts for half of the growth in the US over the past three days. If I removed NY, the US Confirmed Case Count is 11,468, which is within spitting distance of my Hubei-based forecast AND the logistic model.

Date	Forecast Cases: Hubei Pattern	Forecast Percent Growth	Actual Cases	% Daily Growth in Actual Cases	% diff: Actual-Forecast Cases	Logistic Forecast: 1/(1+exp(-( -3.2392+0.1988day of the epidemic)))41500	% diff: Actual-Logistic Forecast Cases
3/14/20	2,999	38.0%	2717	25%	-9%	3,315	-18%
3/15/20	3,552	18.4%	3478	28%	-2%	3,974	-12%
3/16/20	4,376	23.2%	4645	34%	6%	4,748	-2%
3/17/20	6,837	56.3%	6362	37%	-7%	5,650	13%
3/18/20	8,271	21.0%	7769	22%	-6%	6,693	16%
3/19/20	10,202	23.3%	13680	76%	34%	7,885	73%
3/20/20	12,029	17.9%	19285	41%	60%	9,233	109%
3/21/20	13,526	12.4%	24493	27%	81%	10,739	128%
3/22/20	15,264	12.8%	.	.	.	12,395	.
3/23/20	16,577	8.6%	.	.	.	14,189	.
3/24/20	18,125	9.3%	.	.	.	16,099	.
3/25/20	19,408	7.1%	.	.	.	18,096	.
3/26/20	20,410	5.2%	.	.	.	20,144	.
3/27/20	20,410	0.0%	.	.	.	22,204	.
3/28/20	29,488	44.5%	.	.	.	24,236	.
3/29/20	33,280	12.9%	.	.	.	26,201	.
3/30/20	34,408	3.4%	.	.	.	28,066	.
3/31/20	35,590	3.4%	.	.	.	29,806	.
4/1/20	36,696	3.1%	.	.	.	31,401	.
4/2/20	37,731	2.8%	.	.	.	32,842	.
4/3/20	37,945	0.6%	.	.	.	34,125	.
4/4/20	38,196	0.7%	.	.	.	35,255	.
4/5/20	38,331	0.4%	.	.	.	36,238	.
4/6/20	39,201	2.3%	.	.	.	37,086	.
4/7/20	39,201	0.0%	.	.	.	37,811	.
4/8/20	39,325	0.3%	.	.	.	38,427	.
4/9/20	39,630	0.8%	.	.	.	38,947	.
4/10/20	39,875	0.6%	.	.	.	39,384	.
4/11/20	40,125	0.6%	.	.	.	39,749	.
4/12/20	40,320	0.5%	.	.	.	40,054	.
4/13/20	40,579	0.6%	.	.	.	40,307	.
4/14/20	40,927	0.9%	.	.	.	40,517	.
4/15/20	41,047	0.3%	.	.	.	40,691	.

Despite my forecasts continuing to be way off, the rate of growth in the US slowed for the second day in a row. It's also worth noting that NY accounts for half of the growth in the US over the past three days. If I removed NY, the US Confirmed Case Count is 11,468, which is within spitting distance of my Hubei-based forecast AND the logistic model.

Date	Forecast Cases: Hubei Pattern	Forecast Percent Growth	Actual Cases	% Daily Growth in Actual Cases	% diff: Actual-Forecast Cases	Logistic Forecast: 1/(1+exp(-( -3.2392+0.1988day of the epidemic)))41500	% diff: Actual-Logistic Forecast Cases
3/14/20	2,999	38.0%	2717	25%	-9%	3,315	-18%
3/15/20	3,552	18.4%	3478	28%	-2%	3,974	-12%
3/16/20	4,376	23.2%	4645	34%	6%	4,748	-2%
3/17/20	6,837	56.3%	6362	37%	-7%	5,650	13%
3/18/20	8,271	21.0%	7769	22%	-6%	6,693	16%
3/19/20	10,202	23.3%	13680	76%	34%	7,885	73%
3/20/20	12,029	17.9%	19285	41%	60%	9,233	109%
3/21/20	13,526	12.4%	24493	27%	81%	10,739	128%
3/22/20	15,264	12.8%	.	.	.	12,395	.
3/23/20	16,577	8.6%	.	.	.	14,189	.
3/24/20	18,125	9.3%	.	.	.	16,099	.
3/25/20	19,408	7.1%	.	.	.	18,096	.
3/26/20	20,410	5.2%	.	.	.	20,144	.
3/27/20	20,410	0.0%	.	.	.	22,204	.
3/28/20	29,488	44.5%	.	.	.	24,236	.
3/29/20	33,280	12.9%	.	.	.	26,201	.
3/30/20	34,408	3.4%	.	.	.	28,066	.
3/31/20	35,590	3.4%	.	.	.	29,806	.
4/1/20	36,696	3.1%	.	.	.	31,401	.
4/2/20	37,731	2.8%	.	.	.	32,842	.
4/3/20	37,945	0.6%	.	.	.	34,125	.
4/4/20	38,196	0.7%	.	.	.	35,255	.
4/5/20	38,331	0.4%	.	.	.	36,238	.
4/6/20	39,201	2.3%	.	.	.	37,086	.
4/7/20	39,201	0.0%	.	.	.	37,811	.
4/8/20	39,325	0.3%	.	.	.	38,427	.
4/9/20	39,630	0.8%	.	.	.	38,947	.
4/10/20	39,875	0.6%	.	.	.	39,384	.
4/11/20	40,125	0.6%	.	.	.	39,749	.
4/12/20	40,320	0.5%	.	.	.	40,054	.
4/13/20	40,579	0.6%	.	.	.	40,307	.
4/14/20	40,927	0.9%	.	.	.	40,517	.
4/15/20	41,047	0.3%	.	.	.	40,691	.