The article is pretty clear that most of the light-damage, no-injury accidents don't get reported, and that all 11 accidents fell in that category. Half the point of the article is that this data is not well known.

Granted, taking those 1.45 and 55% figures, we might compare the 11 accidents to approximately 3.2 accident (reported and unreported) per million miles in passenger vehicles. Emphasis on "approximately".

That 11 accidents is per 1.7 mil miles so the number you would want to compare is 6.5 not 11.

That said, I don't think you can compare those numbers because it really isn't clear what that "55%" number is supposed to mean.

Doing my own back of the envelope:

~3 trillion miles driven in 2010

drivers involed in PDO (property damage only) crashes: 18.5 million People injured in crashes in 2010: 4 million (from http://www-nrd.nhtsa.dot.gov/pubs/812013.pdf page 143) These numbers include estimates for unreported accidents

Expected crashes for self driving cars based on the above number 6.2 crashes per million miles 1.3 injuries per million miles

Actual number of crashes per million miles (11/1.7) 6.5 crashes per million miles 0 injuries per million miles

Of course, we have no idea if this comparison is at all valid. Given that the incidence of accidents is highly dependent on the ratio of highway miles to street miles, I doubt the comparison is at all accurate. I suspect that since the greatest challenge to self driving cars in on streets, self driving cars have traveled a higher ratio of street to highway miles than normal.

So it would seem purely based on these numbers that the Google cars have had about 4.5 times the mean rate of property-damage-only crashes. However, these statistics don't show us what the shape of the curve looks like, so we have no idea what percentile the Google cars are in.

If we take Google at their word that not one of the 11 crashes was caused by the self-driving system, then these numbers aren't evidence against the self-driving car being safer even with human drivers sharing the road. It's possible the car was driving unsafely in some way that increased its risk of accident without ever directly causing them, but we can't even guess at that without knowing the probability of their crash rate being this distance from the mean by pure chance.

So, do you really think the roads will only be safer when all cars are self-driving--you don't believe there will either be an incremental benefit in overall safety as more self-driving cars get on the road, or a specific safety benefit to owners of self-driving cars?

I think it's important to note that the 11 accidents the self-driving cars were involved in were the fault of the other driver.

At fault doesn't always mean "sole contributor" to the cause of the accident.

> Large Truck and Bus Crash Facts 2012