COVID-19/Guy vandegrift

A good way to highlight approximate symmetry between two data sets is to graph them on a single axis, using each side of the axis to present similar data. This is routinely done with demographic charts.

US and UK COVID daily cases and deaths

The first thing that caught my eye was the sudden shift in the relationship between cases and deaths starting at the end of 2021. Cases in both UK and US are surging dramatically, while deaths remain surprisingly constant.

A survey of what can and cannot be deduced from these graphs make for a good lesson on the interpretation of data and graphs. We will see that a chart like this asks more questions than it answers. The most obvious question is this:

Is the absence of increased deaths in this recent wave due to the fact a new and less deadly variant is taking over?

... Or is it due to the fact that there is always a delay in death rate as patients admitted to hospitals perish days or even weeks after being admitted?

It must be emphasized that a single graph cannot answer this question. But a reasonable guess can be made by observing lags in death rates. In all cases, the surge in deaths starts almost immediately after the surge in cases can be observed. It must be emphasized that in a complex situation like this, definitive conclusions rarely occur. In this case, we cannot rule out a large number of alternative explanations.

Student exercises:

1. List and describe as many possible explanations for a steady death-rate in the face of a sudden increase in cases. In making this list, do not utilize other information you may or may not have regarding the current situation. For example, if you follow news you might know whether or not hospitals are functioning properly during this latest surge. But the graph does not contain that information. So based on the graph alone, we cannot exclude the possibility that hospitals in the UK and US are not functioning properly. This "rule" will make it possible for students to create very long lists (e.g. better medical knowledge to treat patients with specific disease, ...).
2. Note how the peaks in case and death rates seem to be narrower for the UK and the US. In other words, periods (waves) of infection seem to last longer in the US.
   1. Postulate an explanation for this based on the difference in geographic size of the two regions.
   2. Use this explanation to suggest an explanation for why cases in the UK drop almost to zero between waves, while cases in the US never to go to (almost) to zero.
3. List all the reasons why neither the case rates nor the death rates can be used to compare the quality of health care in the US to the UK.
4. This question requires an understanding of calculus: Note that the the peak death rate tends to be higher for the UK than for the US. Explain why this can partly be attributed fact that peaks are wider in the US. Hint: The number of people who get sick (die) is the time-integral of the case (death) rates shown in the graph.
5. Click this link to the demographic charts describe in the introduction.
   1. What language is this wiki use? You might need to play with google translate to answer this question.
   2. The previous exercises allowed us to compare COVID in the United States and United Kingdom. What two populations do the demographic charts you just visted compare?

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