How to read the graph?
On any given day, health officials across Canada provide their case status for the previous 24 hours. They all provide the following: number of new cases, resulting total number of cases, number of patients in hospital, number of patients admitted into intensive care units (ICU) and the number of patients who have passed away.
To prepare the main graph, all cases reported are divided into groups so that each case belongs to one, and only one, of the following groups:
- Passed Away - Black
- In ICU - Red
- Hospitalized (not ICU) - Orange
- Out of Hospital Care - Yellow
- Recovered - Green
Those are graphed as a stacked bar.
The size of the stack for any day is the total number of cases on that day.
Active cases (Red + Orange + Yellow) are stacked from zero. Thus the top of the yellow bars provides a visual curve for the Active Cases over time.
Hospitalized total (Red + Orange) is also stacked from zero. The top of the orange bars provides the Hospitalization curve.
Recovered cases are stacked above the Active Cases. The green bar above the active cases represents cases for which health care is no longer needed. The count of those who passed away is stacked below. The depth of the black bar below zero is the loss from the epidemic.
The blue bar chart on the top left lists New Cases. The blue line across the bars is a simple 7-day moving average. This is commonly referred to in the media as "the curve". Title lists change from the day prior.
The yellow-orange-red bar is the Active Cases graph. It shows the status, share and count of current Active Cases. Title lists change from the day prior.
The green-black bar is the outcome graph. On any given day, all cases with an outcome, either recovered, Probably Recovered, or sadly passed away, are counted and recovery % is calculated. The green-black Outcomes bar represents a “best guess” as to the final outcome of the epidemic. Title lists change in counts from the day prior.
To what date is the data current?
Top left corner of the each graph is a date to which the graph is current. For the provinces it reflects the last date on which data was reported by the province. For the national graph it reflects the last day it was updated by aggregating provincial data. The national graph is only updated on days when all provinces where the disease has yet to be contained have provided a report. As a result, starting June, 2020 there are no longer weekend updates to the national graph.
Data reported on any given day relates to a period prior to the reporting time. Note that there is no consistency between the provinces (or even within a province) as to how that period is framed. For example, if a graph says June 5, 2020, the data will reflect what was last updated on June 5th. It will generally refer to an aggregate of patient status at some point in time on June 4th.
Why Probable Recoveries in Quebec and how are they Calculated?
After the initial days of a disease spread, the number of daily New Cases and the number of Active Cases should correlate in some manner. This phenomenon can be observed by comparing the trend in the number of daily New Cases (blue line in blue graph to left) to the trend in Active Cases (top of yellow bar in main graph). One would expect both graphs to generally look similar, and this is indeed the case in most provinces. Quebec was different. While the number of daily New Cases there peaked in early May, 2020, the number of Active Cases kept trending up.
To quantify what is visually noticeable, we can took the reported number of Active Cases in each province and then check how many days back we would have to go accumulating New Cases in order to fulfill that number. Over time the three bigger provinces (ON, BC, AB) all generally had an Active Case count that is less than the cumulative number of New Cases in the past 20 days. Quebec's reported number of Active Cases required an ever growing number of days to fulfill. It was thus underreporting recoveries.
To correct the underreporting, the number of Active Cases in QC was capped at the total number of New Cases over the past 21 days. Probable recoveries are derived from that. On July 17, 2020. Quebec significantly updated number of recoveries. It now falls within reasonable limits.
Why Probable Recoveries in BC and how are they Calculated?
The number of Active cases should equal to the total number of cases minus recoveries minus patients who passed away. Since August 26, BC is reporting an Active Cases number that is below what is calculated using the above. The 'unaccounted' for cases are assumed to have recovered.