L-Moment estimation of Burr III parameters

The Burr family of distributions has been used extensively for over 20 years as a species sensitivity distribution (SSD) in ecotoxicology. Indeed, its popularity (at least in Australia and New Zealand) has been guaranteed by the fact that it is a default distribution in the Burrlioz software tool which underpins the methodology for guideline development (GV) in those countries. The main advantages of the Burr distributions are (i) they can accommodate a wide variety of …

COVID-19: Modelling Explainer

So how did we obtain the predictions made in the previous posts? Well, it’s by a process of complex mathematical modelling. We won’t go into the details here, but instead will try to explain with the help of a few graphs for Victorian data. First – let’s look at the actual number of cases per day and the cumulative tally: We next fit a complex mathematical model to the cumulative curve above. This gives us …

COVID-19 Australia: Revised model

Disclaimer: We have high levels of expertise in statistical modelling. We are not epidemiologists. Modelling is an imprecise science. As renowned statistician G.E.P. Box once remarked “all models are wrong – but some are useful”. In our earlier post of April 5 (see below) we estimated that the number of diagnosed positive cases in Australia would plateau at 6,195 by April 20, 2020 (day 90 on the plots below). In a subsequent update, it was …

COVID-19: Model comparisons for Australia

Updated: April 11, 2020 Disclaimer: We have high levels of expertise in statistical modelling. We are not epidemiologists. Please refer to our previous post for state-by-state predictions for the number of COVID-19 positive test results. We will add actual data to the graphs of model predictions to assess how well we’re tracking. The latest data are displayed below. The blue line is our fitted model; the solid red line are the predictions; the horizontal purple …

COVID-19 Australia – When will it peak?

Disclaimer: We have high levels of expertise in statistical modelling. We are not epidemiologists. Based on a preliminary analysis of Australian data for the number of COVID-19 infections, we believe there has been a recent slowing down of the rate of infection. If this trend is maintained, we predict the total number of infections in Australia will stabilize around 6,195 by April 20, 2020. Specifically: ACT: 101 cases NSW: 2,795 cases NT: 32 cases QLD: …