By 11 PM on Tuesday, India's Covid-19 positive cases crossed the 30,000 mark.  To be precise, the total number of confirmed cases was 31,284 and 977 deaths amid Maharashtra and a few other States continuing to throw up big numbers.  

In terms of detection rate, India has got a piece of positive news.  "12 days ago, only 4.7% of all those tested were found positive.  Some people incorrectly argued that low testing was to blame.  Now, 12 days later when testing has increased by over 100% and 40,000 tests per day are taking place, our positive detection rate is even lower, just 4.1%," a report says.  

Economist Rupa Subramanya differs and asks, "Who is being sampled? If you are testing those in hotspots, those who show COVID-19 symptoms, and you increase the testing and infection rates goes down, that is good news. However important to put confidence bounds around those numbers. Is 4.7% to 4.1% statistically different?"

But is that all?  Writing in Business Line, Amitabh Kant of NITI Ayog analzyed that it would be incorrect to assume that higher testing implies a higher positive detection rate.  "A case in point is Germany, which is carrying out the highest number of tests per million population (approximately 25,000), and yet detection remains at 7.26%," he writes.