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Re: [jt512] Possible legal action against CCH Inc.:
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ja1484
Jun 20, 2007, 5:12 PM
Views: 4145
Registered: Aug 11, 2006
Posts: 1935
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jt512 wrote: Well, I read your original post twice before replying, and was pretty perplexed by it; and now I have read it again, and am still pretty perplexed. Either we really do disagree, or you have not explained yourself very well. Let's look again at the claims in your original post: In reply to: If you crunch the numbers, eventually it is a mathematical certainty that a cam will get through quality control and be primed to fail at 1 - 2kN. That depends on what you mean by "eventually." If by "eventually" you mean eventually in finite time, then, no, it will not eventually happen. Human beings will have ceased to exist eons before enough cams could ever be manufactured so that it might be possible for one to fail at -19 standard deviations (SD).
I'm speaking purely in terms of the numbers in theory - on paper. Not taking into account pesky little things like "reality". So in essence, no, I'm not talking about finite time. Assume we continue manufacturing cams ad infinitum. I'm crunching numbers, not putting the numbers into practice.
Pointless? Yes it is, which is exactly why I mentioned to dynosore that he might want to stop thinking about the situation in absolutes.
In reply to: We noted that the probability of a -19 SD event is about 1 / 10^80. Now, the Big Bang is estimated to have occurred 13.7 billion years ago. Now, even if 1 billion cams were produced every second since the Big Bang until now, "only" about 10^25 cams will have been produced. This is still 55 orders of magnitude less than the number of cams needed for us to expect to produce a single cam that would fail at -19 SD. So, since even on a cosmologic time scale, "eventually" no cam could fail at such a low load, it is certain that on a human time scale, no cam could fail.
All this is exactly why I feel fine climbing above 3Sig certed equipment. Again, previous statements were regarding the infinite world of numbers. See above.
The thing I always like about this though is that (on a slightly tangential note) people always assume it's that last cam in the 10^80 batch. Why not the first? Or perhaps the 7th? Just wondering.
Regardless, I still trust my gear.
In reply to: Well, I just did crunch them, and we saw that no, it will never happen to someone, guaranteed.
Yes, but you related the results to our real-world situation, not the straight math. Looking purely at the numbers and leaving assumptions off the table, that -19 SD failure is still there, no?
In reply to: Conclusion: Under realistic assumptions, it is statistically impossible for a cam belonging to a population purported to have a 3-sigma breaking strength of 10 kN to break at 2 kN under normal use. Jay
Agreed.
Edit: This is all, of course, assuming that quality control checks were accurate. When you bring human error into the process, things get quite a bit more complicated, which is why, despite the big fancy numbers, there are occasional gear failures under proper use and within acceptable loads (a recent example being that Omega link cam that had been placed a few times and never weighted having a lobe fall off). This stuff isn't so easy to calculate (if possible at all), and is the real-world, finite time "x-factor" - what people should actually be worried about if they're going to bother worrying at all.
(This post was edited by ja1484 on Jun 20, 2007, 5:21 PM)
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Post edited by ja1484
() on Jun 20, 2007, 5:14 PM
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Post edited by ja1484
() on Jun 20, 2007, 5:16 PM
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Post edited by ja1484
() on Jun 20, 2007, 5:21 PM
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