Understanding Pandemic Statistics

Real examples help to better understand how to interpret the statistics.

False Positive Paradox: A particular medical test for a disease is 96% accurate. If one has the disease, the test comes back ‘Yes’ 96% of the time, and if one does not have the disease, the test comes back ‘Yes’ 4% of the time.

If  100  of 10000 tested patients have the disease, what is the probability that the person with the diagnosis ‘Yes’ has the disease?


Effective Average Infection Ratio: R is the effective average infection ratio for a disease, also known as the reproduction number. It is the average number of secondary infections caused by one person. (Infections caused by the secondary infections – which would be tertiary infections – are not counted). Consider 50 infected people. Suppose 49 spread the infection to nobody, but one person spreads the infection to 60 people.

What is the R-value?


Leslie Green asks: How would you propose to deal with the COVID-19 pandemic, given information current at the time of writing (11 October 2020). 

A. Severe lockdown for 4 weeks

B. Ignore it and carry on as normal

C. Partial lockdown and wait for a vaccine

D. Some other idea


We Lack Numeracy Skills

Alan Smith reported amazing statistics of adult numeracy:

2011 England Survey: 49 of 100 adults lacked of numeracy Level 1 skills (fractions, percentage, and decimals).  The figure is only shocking for 51% of population.

OECD reported (PIAACX2012) that forty percent of USA young people aged 16-19 were below Level 2.

This is statistics. Statistics is a part of mathematics and it is about us as a group.

There are two categories of people who can and who cannot do numbers.

Are You in a category of people who are comfortable with numbers? Check / train yourself at the website A+Click