COVID-19 SCIENCE

# Misleading modelling or did Victoria's stage three lockdown really avert up to 37,000 cases?

Victoria had the harshest lockdown in Australia and yet once lockdown finished had a resurgence in cases which led to a Stage 3 lock down and further hardship and flattening the economy even further.

To justify the new lockdown the headlines read “Victoria's stage three lockdown in July averted up to 37,000 coronavirus cases and saved 1,258 lives, research finds.”

This conclusion was based on modelling by a Victorian Institute, whose name we do not wish to disrepute. The statement itself was wrong because it was a statement of fact, not a statement of possibility. Models are always wrong and hence the statement cannot be a statement of fact.

The statement is a propaganda statement because it does exaggerate the perception of truth by saying ‘up to 37000 cases’ when the Institutes report stated 5000 to 37000 cases. This invalidates the saved lives statement. If only 5000 cases were averted, then lives saved would have been around 170.

The ‘model’ is based on an INCORRECT assumption of exponential growth. Figure 1 shows the actual data which can be obtained from: https://www.dhhs.vic.gov.au/victorian-coronavirus-covid-19-data which is the data source used by the institute.

Figure 1: Victoria’s cases between June 14th and August the second

There is no exponential growth. There are three linear segments as shown in Figure 2. Exponential growth occurs in a theoretical test tube environment but not necessarily in the real world.

Figure 2 Three Linear segments

One can stretch the imagination and approximate section 1 and 2 with an exponential curve as shown in Figure 3, but stretching the imagination is not a scientific process.

Figure 3. A fitted exponential curve.

If we extrapolate the curve in Figure 3 it will appear that we would have had far greater cases and deaths to follow. But that is not reality.

The Institute assuming an exponential curve plotted the logarithms to base 10 and obtained a chart like that in Figure 4.

Figure 4: A plot of the logarithm of reported daily cases

Referring to Figure 4, one will observe two sections. One with a blue slope and one with a red slope. Because the slopes of the logarithms are linear the Institute assumed two exponential growth curves. One prior to lockdown and the other post lockdown.

Appendix A.3 in the downloadable full report shows that linear logarithmic transformed lines does not prove exponential growth.

The institute then used this misinformation to calculate averted cases and concluded that -

Victoria's stage three lockdown in July averted up to 37,000 coronavirus cases and saved 1,258 lives, research finds.

Referring to Figure 1 there is no sign of an effect on cases after the lockdown was implemented after 30 days. In the previous snippet “Deceptive Mathematics or did Victoria, Australia need Lockdown 4?” Victoria made it clear that one would expect a reaction after 4 days.