Two people killed in fiery Tesla crash with no one driving
Some people are quoting the recent Tesla safety report [1] as evidence that Autopilot is on average much safer than a human driver. This is a classic case of the Simpson's Paradox [2].On the first look it seems that Autopilot is 4x safer than driving without any safety features (1 accident every 4.19 million miles vs 0.978 million miles). However, the data used to compute the stats is different in two important ways:1. Autopilot cannot be always activated. This means that is some particularly difficult situations, the driver needs to drive himself. These are more dangerous situations in general.2. If a driver disengages Autopilot to avoid an accident and engages it again straight away on a 10 miles drive, then you will have 9.99 miles driven on Autopilot without accident. The statistic misses the cases where the human driver intervened to avoid an accident.This means that we are comparing the same measure (accidents) on different datasets and therefore in different conditions. This is dangerous, because it may lead us to wrong and often opposite conclusions (see Simpson's Paradox [2]).I'm not saying that Autopilot isn't safer than a human driver, given that the driver is at the steering wheel and alert, but that this data doesn't lead to that conclusion. If the driver is not sitting at the driver seat, then it is certainly much more dangerous.[1] https://www.tesla.com/VehicleSafetyReport
[2] https://en.wikipedia.org/wiki/Simpson%27s_paradox