Sunday, June 7, 2020

The model predicting 'massive' increase in COVID-19 cases in Mobile badly missed the mark

A model that used social mobility data from May to predict a huge upswing of June COVID-19 cases in Mobile County didn't even come close. posted this news item from respected investigative reporter Brendan Kirby on May 22, 2020.
Even as Alabama moves to lift more restrictions imposed to fight the novel coronavirus, a new model suggests the state’s hardest-hit county is poised for an explosion of new cases.

The forecast, produced by the Children’s Hospital of Philadelphia Policy Lab and the University of Pennsylvania, projects a six-fold increase in Mobile County’s daily average of new cases by the middle of June.

Unlike some other models, it is less concerned with the official polices in place and focuses more on what actually is happening on the ground. It includes factors like heat and humidity, which tend to slow the virus, and attempts to measure how well people are “social distancing.” As a proxy for that, the model uses cell phone GPS data from Unicast to determine how often people are going to “non-essential” businesses.
The model predicted a rate of new cases reaching 45/day on Memorial Day, then rising to more than 350/day by mid-June. The article is scary. Had you read it when it was published, you might have thought Mobile was in line for a disastrous few weeks.

It hasn't even been close.

I encourage you to follow the link to Kirby's report, and watch the two minute video. Pay particular attention to Rubin's comments.

Today is June 7 in the Year of our Lord 2020, a day on which there should have been a whopping 140 newly sickened patients. The actual number of new cases today: 56. That represents a significant increase from yesterday's observation of 25, but the jump has absolutely nothing to do with social distancing regime that was in place last month. Social distancing is the most influential predictor in the Children’s Hospital of Philadelphia, according to what Director David Rubin told Fox10. If anything, Mobile County has gotten worse in social distancing since  mid-May, not better. The intervening period includes high school graduations, the Memorial Day Weekend and days of public protesting. We may yet see an increase in positive COVID-19 cases as result of all of this highly social interaction, but we have no chance of seeing the dire trend predicted by this model. 

More than two months ago, this blog examined another model that predicted death and devastation for our fair state. That model also used specious data to produce a super scary forecast, and that one has also thankfully proved inaccurate. The Institute for Health Metrics and Evaluation's COVID-19 projections were garbage in April and are still garbage today. Yet Fox10 (and others) still portray them in pages on their websites. Why?

The chart below shows just how awful IHME has been in predicting the coronavirus pandemic in Alabama.

The bold, jagged brown line shows the daily confirmed infections statewide. The dashed line shows the model's predictions for infections. Since record keeping began and IHME has been producing forecasts, the model has horribly and consistently missed the actual case rate.

The chart I've included also shows a shaded area that represents the uncertainty interval for the model's results. The best way to understand that is to say, "there is a 95% chance that the actual result will fall with in the shaded area." The actual result almost never has.

The IHME model and the model produced by Children’s Hospital of Philadelphia both use their assessment of social distancing as a primary driver predicting infections, and both have produced garbage results.

Government officials and the media have been consistent in driving home the need for restrictive social distancing, and using these demonstrably worthless predictive models to convince people that if they don't practice proper social distancing, very bad things will happen.

Interesting, no?

Think of it this way: You saw the news reports in March and April. You saw the model predictions of a runaway virus killing people by the thousands in your community, and the officials' fervent pleadings and outright directives that you follow this new normal, or else. Now, you've learned that the models they used to force your compliance are garbage.


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