On the COVID-19 outbreak in Italy
- The subsequent analysis is based on
provided by Protezione Civile.
- Data timeseries start on February 24, 2020 (hereafter, days
`-5 of March').
- The analysis has been done using Wolfram Mathematica. The
code we used is available here.
- We fit cumulative data (cumulative number of confirmed cases,
or of fatalities) with
function (blue) and
- We fit daily data (number of infectious daily fatalities) with
distribution (blue) and
- In the best fit procedure, we assume that data of
magnitude n are affected by an
error ± √ n .
- Only the first part of the data (black dots), till the
date indicated in each plot, is used for the fit.
- Remaining data (red dots)
are NOT used for the fit, but just reported as a check of the
predictivity of the two curves.
- For each plot we report:
- "date" is the date of the best fit: only data earlier than
"date" have been used (NB: "33 March" means "2 April", etc.);
- "t0" is the best fit value for the date of
the peak (or, for cumulative data, of the inflection point),
for the considered quantity;
- "A" is the best fit value at peak (or, for cumulative
data, at inflection point), for the considered quantity.
- The analysis suggests that, when the outbreak is still at
its early stages (say, before its peak), fits of available
empirical data by the error function (or normal distribution) could be
more predictive than those by the logistic function (or logistic
- Note added on 2 April 2020: concerning
daily fatalities, whose peak is presumably already
behind us, in the most recent fit, the logistic distribution is
starting to perform better than the Gaussian distribution.
- Note added on 3 April 2020: Having now sufficient data, we
have made a check of the compliance of fits made
one/two/three weeks ago with subsequent data.
Cumulative confirmed cases
Best fits of 12 March 2020, against subsequent data till April 16
Best fits of 22 March 2020, against subsequent data till April 16
Best fits of 32 March (April 1) 2020, against subsequent data till April 16
Best fits of 42 March (April 11) 2020, against subsequent data till April 16