Story. This data represents the number of COVID-19 cases worldwide from January 20, 2020 (t=1) to March 8, 2020 (t=47). Graph the data on Desmos

Number of COVID-19 cases worldwide from January 20, 2020 to March 8, 2020

13. How accurate was your Model 1? Explain the differences
between Model 1 and the new data set on the left. What do you think
caused these differences?
14. On the graph, identify some important day(s) and give a rational
of what is happening.
15. Your job is to develop a model that accurately predicts what is
going to happen. Given the new data set on the left, develop a model to
predict the behavior of the disease (Model 3).

Model 3: Total cases (logistic function)

Logistic function model

Model 1 is not accurate in predicting the long-term spread of the virus. According to the data, the total number of cases did not grow exponentially from day 20 to day 40. The exponential model greatly overestimates the number of people infected. The number of people actually infected is lower than the predicted number of infections using the exponential model partly because at some point the virus begins to run out of people to infect and partly because policies such as “social distancing” are enacted to limit the spread of the disease. Day 22 is an important day because the number of people infected increases by a large extent and does not follow the previous pattern. The number of cases probably rises by such a large extent because there is a change in diagnostic criteria. For example, testing and reporting may be increased. The above model, Model 3, is a logistic model used to predict the number of cases in the future.