Document data cleaning method & motivation

[jaryaman]

• How we get the "7-Day Average"
• How we clean and present the raw data for number of cases, and number of new cases

[kinabalu]

this should be a page describing any calculations we make to arrive at data, similar to the predictions methodology page, but just a simple, here's how we calculate new cases, rolling average, the rate graph, etc, etc.

[jaryaman]

• 7-Day Average: The smoothed number of new cases is calculated as the average of the current day's number of new cases, and the preceding 6 days of data.

• Rate: Total number of cases presented on a log scale, beginning from the first day with >=100 cases

• Case Fatality Rate: The ratio of the total number of deaths to the total number of confirmed cases

I will let @pr3d4t0r discuss new cases...