[marcosdumay]

> Proper statistical analysis would help you there.

Yes, if you know the probability distribution. If you don't know the distribution, you can not calculate your confidence, and thus can not do a proper statistical analysis.

And, guess what, nobody knows the probability distribution of hard drive failures. That's exactly what they are trying to find out.

[xixi77]

There are actually many methods in survival analysis -- just as in the rest of statistics -- that do not impose strict distributional assumptions, and account for the fact that many drives are still operational. But as someone else mentioned, the median is also a good statistic to report :)