Countries around the world are working to “flatten the curve” of new cases of Coronavirus pandemic.
As statistics and statistical models are very powerful tool in data driven decision making (DDDM), I derived inferences related to flattening of COVI19 curve by analyzing data up to 05th May.
DDDM involves making decisions that are backed up by inferences derived by statistical analyses of observed data rather than making decisions that are intuitive or based on observation alone.
Daily Trend of COVID19 Cases
During the period from 11th March to 05th May, the probability of getting less than or equal to 10 new confirmed cases per day is 0.64.
The corresponding probability for more than 25 cases is 0.16. This was due to the observing more than 25 cases consecutively for seven days. Nevertheless, I believe it was an unusual phenomenon that happened against the natural course of the disease.
In fact, this has been realized by the government appropriately and immediate remedial measures were taken by the government to avoid a resurgence. Those points are considered as influence points which impact to the natural pattern that we have been observing.
To reduce the noise, the trend was plotted for 5-day median (Fig.1). This is a better outlier resistant smoothing technique than 5-day moving averages. It can be seen that the median has been decreasing from 52 (25 April) to 27 (30 April) in spite of outliers. This pattern is an indication that the new cases are flattening in Sri Lanka. Thus, it can be concluded by middle of May curve will convergent to smaller number of cases.
Trend in % Increase of Daily Cumulative COVID19 Cases
Fig. 2 has a clear exponentially decreasing trend and in fact most of percentage are very low (< 10%) in particularly as the time passes. That is also a clear indication of flattening the dally new cases of COVI19.
Recommendation
Covid19 Curve in Sri Lanka will be flattening by middle of May. Government can relax various restriction so that business can start and people can come back to normal life. However, people should be susceptible to follow the “intra vires” instructions given by the health authorities even after the situation back to normal. Data driven decision making (DDDM) is a powerful tool for effective decision making.
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