"It’s pretty ubiquitous and we need to pay attention to it."
During World War II (1939-1945), pilots were interested in ways to make their fighter jets more resistant to getting shot. To this end, the Allied forces at least would inspect jets that returned from sorties and check where the bullet holes were. Then they would reinforce those areas and send the planes back.
Fortunately for them, a statistician realised that this ad hoc solution wouldn’t improve the plane’s chances very much: the location of the bullet holes were actually where the planes could take a hit and still not go down. So he directed the air force to reinforce parts of the planes that hadn’t yet been hit.
The intuitive urge to make decisions about survival based on what has survived is called survival bias.
Something similar could’ve been happening to our understanding of groundwater levels in South India. Several papers published recently claimed that groundwater levels have been on the rise and had the data to show for it. They used government records on groundwater levels in wells together with data from a NASA satellite called GRACE, which can deduce underground water content using the water’s minute gravitational effects.
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