The way the math works, is estimates for a certain day are used in calculating the estimate for the following day, so yes, the future numbers build upon previous numbers.
But you used the present DFR for your estimate of the future deaths in your graph?
Yes, you can not get any more accurate numbers than the last reported actual numbers, of course that depends upon how accurate the data itself is. So nightly, I rerun the projection which corrects all numbers down the line based on the best available information. That's how hurricanes are tracked.
As to the uniqueness of the slope, and time length I feel okay in going with, only about 40 days now, I determine, by eyeballing, technical analysis of the US slope, and other country's slopes, and just a plain ol' SWAG of where I think 'the barrier' is and at what date we will hit it. I've arbitrarily plugged in 3% - probably a little too optimistic, and a date of 23 April, IIRC.
'The barrier' is what I saw countries like Korea, Italy, and Spain run into near lower DFI numbers.
For a week or two, these countries oscillated near the 3% level. This doesn't sound like much, until you realize it is an increase of 3% of total deaths every day, and that increase builds upon itself.
In Korea's case which has a low total number of those who have died from the corona virus, new death numbers aren't that high compared to Italy. In Italy's case the total number who have died is high. So even at a low 3% DFI, Italy's number of those who are still dying is very high indeed.
I believe we're going to see a similar pattern in the US. Our DFI, which is about 7% as of last night, is still high. The US is leading the world in number of deaths at 22,105 as of last night. IMO, that means the US may see large numbers dying, even at low DFI numbers.
The the law of exponential growth reasserts itself and numbers start growing rapidly again at 'the barrier'. No epidemiologist here, but to me, this could help explain what epidemiologists often see/call a resurgence.
To end on a positive note, Korea/Italy, are bumping down as low as 1.5% now. That is very encouraging. I want to add the above is from my own observation and YMMV. Let's pray a cure will be available very soon.
China Quietly Reimposes Restrictions On Movement As Outbreak's 'Second Wave' Looms
You’re not giving your metric a chance to prove itself.
To show my point (Without resorting to math I haven’t used more than half a dozen times in 50 years...)
Say that a week ago you wanted to predict the deaths today.
You should use what was predicted by your metric for today , not what was shown by your metric a week ago.
And to predict the deaths a week from now you should use what is predicted by your metric for a week from now.
Not what it shows today.
Sure slopes and graphs change.
But you’re not giving your graph a fair chance.
Alright, I took my shot.