Self-Driving Car Safety Tests

I read here and there that self-driving cars are proving safer than human-operated vehicles. What is the actual research behind this claim? Does it involve putting self-driving cars on the road with other, non-self-driven cars, in a variety of road conditions etc?

Here’s a blog post by the guy at Google in charge of the overall self-driving car project: http://googleblog.blogspot.com/2014/04/the-latest-chapter-for-self-driving-car.html

Here’s a repost of another blog entry by him about their experience having accidents. https://medium.com/backchannel/the-view-from-the-front-seat-of-the-google-self-driving-car-46fc9f3e6088

The short version is so far they’ve driven a million miles on surface streets & highways amongst real traffic. Plus however much early testing was done on closed courses. And Google is far from the only player in this space.

Here’s the latest blog post from within the last month: http://googleblog.blogspot.com/2015/05/self-driving-vehicle-prototypes-on-road.html