Donald Trump’s Twitter posting on 9 July 2020 establishes a correlation between the corona tests performed in a country and the confirmed Covid-19 cases in that country. Explicitly, he claims for the USA: “For the 1/100th time, the reason we show so many Cases, compared to other countries that haven’t done nearly as well as we have, is that our TESTING is much bigger and better. We have tested 40,000,000 people. If we did 20,000,000 instead, Cases would be half, etc. NOT REPORTED!” Even though the correlation exists, Trump’s claim is mostly false.
According to Donald Trump’s logic, countries that perform as many or more tests than the USA also have more people officially suffering from Covid-19. A first look at the data situation reveals that this is not the case in China because China is the country with the most tests performed worldwide: with over 90,000,000 tests performed, twice as many as the USA. But China with 86,322 cases confirmed has significantly fewer cases than the USA that have counted 3,499,394 so far. This already makes it clear that Trump’s statement cannot be true.
Brazil is also a counterexample to Trump’s claim. With 1,900,000 confirmed Covid-19 cases, Brazil has more than half as many cases as the USA. According to Trump, this would imply that Brazil has at least half of the number of tests performed in the USA, too. However, with 4,911,000 performed tests, Brazil carries out just 10.9% of the number of tests carried out in the USA.
Furthermore, one must consider the so-called “positive rate” in order to assess Trump’s claim. The positive rate describes the proportion of tests in a country that confirm a Covid-19 case by yielding a positive test result. If one followed the logic by Trump, it should mean that the positive rate of all countries is equal.
However, a look at the data shows that the positive rates of the countries vary considerably. Countries with high test volumes show lower positive rates (e.g. Australia: 0.5%) than countries with low test volumes (e.g. Brazil: 38.7%). This means that countries that carry out many tests also tend to collect significantly more negative tests than countries that carry out fewer tests.
Therefore, the statement of the Twitter post can be clearly refuted with respect to positive rates. Finally, at closer inspection, Trump’s statement may also allude to a possible dark figure. By this, he could mean that the number of unreported cases is higher in countries that carry out few tests than in countries with a high volume of tests. The dark figure indicates how many people have contracted Covid-19 but are not included in the official case numbers. For example, people with unnoticeable symptoms may not be statistically recorded because they do not meet the criteria for conducting a test. It is therefore essential to differentiate between the cases reported and those actually infected.
In order to definitely falsify the thesis of Donald Trump, however, a data set that shows the number of unreported cases worldwide would be necessary. Findings on the exact number of unreported cases can be obtained locally in studies (for example in the Heinsberg study in Germany), but it is simply not feasible to obtain global findings on this matter because factors like population density or public mobility vary considerably and affect the spread of Covid-19.
In conclusion, it can be stated that Trump’s statement is clearly refuted on several points and is therefore largely incorrect. However, there is a correlation between the number of tests performed and the number of cases detected because a lot of Covid-19 cases are asymptomatic and therefore only detected with a lot of testing. For these reasons the Twitter post is to be assigned to the category “mostly false”.
Date of data in the text: July 16, 2020
RESEARCH | ARTICLE : Ingrid Bonfert & Luca Schwarz, Hochschule der Medien, Stuttgart, Germany
