• Stephen Grice

Using SIR+B process for calculating the Reff for COVID-19 for various countries

We have continued to refine and improve our SIR+B method for calculating the effective reproduction number for COVID-19 globally.

A sample of our latest results are given below.

The charts show clear exponential growth in COVID-19 positive daily cases in India. The Effective Reproduction Number (Reff) is almost a constant value of 1.5 over this extended period of time. The low amount of noise in the case data results in very small confidence intervals in our SIR+B calculations for Effective Reproduction Number (Reff) above.

It is important to see how our SIR+B method works with a dataset with where there is more noise. Below is a chart of Florida, USA.

The chart of Florida, USA, growth of COVID-19 positive daily case data in April and then the effect of the "stay at home" social distance policies from April until early June. Once the social distance policies are relaxed the positive daily case data increases. The Reff is approximately 1.7 from the middle of June to present. The positive data for Florida has more noise than the data for India. This is reflected in the increased confidence intervals where the 50% confidence level is now visible. The confidence intervals are still relatively narrow showing the confidence we have in our improved SIR+B method.

You can see more real-time global data on our website here.

We have also prepared a results paper on the SIR+B results of our methods which includes other countries. That paper is here.

The mathematics for our SIR+B method and all the techniques are available in this paper here.

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