The heuristic employed is that a higher test positivity indicates a higher count of missed infections, which makes sense. If testing were increasing effectively to capture new infections as they arise, positivity should decline.
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Extending the same method to the testing/daily case reports for the States of India ...
Daily Test Capture | Estimated True Cases
AP: 1500 | 3500
AS: 750 | 2000
BR: 600 | 1800
CT: 150 | 170 (Last testing data NA)
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That said, it's still clear which states are capturing 40%+ of cases.