> It was sort of striking to read Charles Fishman's statement about the software being bug free, followed immediately by the supporting fact that the last three versions had one bug each. If they had one bug, how are you 100% sure they didn't have two?
I think you're being overcritical here. It's really really really difficult to reach 100% in any real form of measurement. So I think when they mean "bug free", they probably mean the chance of a bug is below some threshold of probability. The famous six sigma rule comes in mind.
I do grant you that this is not specified explicitly in the article, but they do say: "each 420,000 lines long-had just one error each. The last 11 versions of this software had a total of 17 errors. Commercial programs of equivalent complexity would have 5,000 errors."
>> So I think when they mean "bug free", they probably mean the chance of a bug is below some threshold of probability. The famous six sigma rule comes in mind.
No doubt, and that was in fact my point. I think most of us would be very reluctant to use the phrase "bug free," and in this case his statement was obviously meant to be in stark contrast to that reluctance.
I think this is more of a technicality that's very subjective. I feel that "no" depends on the probability of something happening as well as how catastrophic it is.
For example, after buying a lottery ticket, I can pretty comfortably say that I'm not going to win. Sure, there is a chance, but is it really going to happen? No.
As another example, if I put down a waterbottle on my bike seat, there's a 1% chance of the water spilling onto the sidewalk. At this point, I'm also comfortable saying that it's not going to happen. However, if the waterbottle has a 1% chance of exploding when I put it down, I don't think I'll be comfortable saying that it won't happen. The chance of that must be much much lower before I can accept it.
I would like to give the person who said that the benefit of the doubt. I'm sure they understand the implication of bug free, but it's likely just easier to say that rather than explaining stats/tradeoffs to a journalist.
I think you're being overcritical here. It's really really really difficult to reach 100% in any real form of measurement. So I think when they mean "bug free", they probably mean the chance of a bug is below some threshold of probability. The famous six sigma rule comes in mind.
I do grant you that this is not specified explicitly in the article, but they do say: "each 420,000 lines long-had just one error each. The last 11 versions of this software had a total of 17 errors. Commercial programs of equivalent complexity would have 5,000 errors."