In looking at this a bit further, it seems that the reliability of the Falcon 9 is not looking so good. It has only flown four times and suffered single engine

In looking at this a bit further, it seems that the reliability of the Falcon 9 is not looking so good. It has only flown four times and suffered single engine shutdowns on two of them (the other: http://www.spacenews.com/civil/spacex-acknowledges-falcon-engine-anomaly-during-latest-launch.html http://www.spacenews.com/civil/spacex-acknowledges-falcon-en...). See also: http://www.americaspace.org/?p=9044 http://www.americaspace.org/?p=9044. Simple probability then gives a failure rate of 3%. I have not attempted the Bayesian analysis.