Fig. 3
From: COVID-19 outbreaks surveillance through text mining applied to electronic health records
The shifted time series of suspected cases of COVID-19 for patients with ages 18 years. For each epidemiological wave, we shift the time series of suspected cases of COVID-19 (in blue) by the characteristic time lag , the time lag associated with the maximum value of the sample cross-correlation , and compare it to the time series of confirmed cases of COVID-19 (in orange). (a)-(c) We find = 72 days and ~0.82, = 25 days and ~0.93, and = 17 days and ~0.88 for the first, second, and third waves, respectively. Despite the high values of in all waves, the last two waves represent a more trustful value of since there was a well-known lack of tests in the first wave of COVID-19