I would like to know at how many pounds of pressure each cam broke.

Basing my response on the assumption that you understand the first sentence in its entirety, the stated p-value (in this case) is the approximate probability that 33.3% or more units would have failed below their rated strength (the observed result) if, in the population from which the tested sample of units were derived, 0.135% failed below their rated strength....
Jay

In my reply to an earlier post I stated that Mountain Gear would test a sample of our in-stock Aliens and post results on this forum. Following are our findings. Please realize that Mountain Gear’s tests results are not “official,” they were not independent, nor did they represent a random sampling of all Aliens.

We took nine units of various sizes and date stamps dating back to the earliest we had in stock which is 0605 for pull testing. Of the nine Aliens tested, three brazes failed and the cable pulled out at below the CCH-stated max strength for that size. The failures were from different sizes and date stamps, and included both Hybrid and regular Aliens.

Since we reported these findings to Dave at CCH, he has been working diligently to identify the source and scope of the problem. I expect that we will see information from him soon. According to Dave, CCH is also reporting the issue to the CPSC (Consumer Products Safety Commission), and will work in concert with them to remove the potentially affected Aliens from the Market. You will have to rely on this process to get the final results of the investigation of these products.

We have also informed REI of our findings and they reacted quickly to work with CCH and Mountain Gear so that there can be a coordinated effort to get the potentially affected Aliens off the market and off climbers racks.

If you bought potentially affected Aliens from Mountain Gear:
We will contact you with instructions on getting them returned, inspected, repaired and/or replaced. We will also post information by Friday 12 p.m. PST on returning potentially affected CCH product at http://www.mountaingear.com/aliens.

Mountain Gear wants the best results for the climbing community. I wish I could tell you more but this is the best information we have at this time. We will continue to encourage CCH to act quickly to thoroughly complete their investigation, and will post more information on our website as we receive it from CCH or the CPSC.

Paul Fish
President
Mountain Gear, Inc

I see what you are saying, but this is not the correct methodology. Let's say that a cam is rated to hold 3000 pounds. We test 10 cams and find out that 2 of them fail at a weight of less than 3000 pounds. This does not tell us a lot.

Now, say we get more data about that same test. Two of the cams failed at 2999 pounds and the other 8 failed at 3500 pounds. If we use a null hypothosis that the cams fail at more than 3000 pounds, then results are not statistically significant and we cannot disprove our null. That is all there is to it.

If we change the assumptions about the data to: 2 cams failed at 1500 pounds and the other 8 failed at 3001 pounds, then the weight at which the cams are failing is going to be significantly less than 3000 pounds.

Mgear has not said at what weight the Aliens failed, therefore, we do not know if they are failing at a strength that is significantly lower than their stated strength. Frankly, if they are failing at 10 pounds less than CCH says they will, I could give a rat's ass.

I see what you are saying, but this is not the correct methodology. Let's say that a cam is rated to hold 3000 pounds. We test 10 cams and find out that 2 of them fail at a weight of less than 3000 pounds. This does not tell us a lot.

Now, say we get more data about that same test. Two of the cams failed at 2999 pounds and the other 8 failed at 3500 pounds. If we use a null hypothosis that the cams fail at more than 3000 pounds, then results are not statistically significant and we cannot disprove our null. That is all there is to it.

If we change the assumptions about the data to: 2 cams failed at 1500 pounds and the other 8 failed at 3001 pounds, then the weight at which the cams are failing is going to be significantly less than 3000 pounds.

Mgear has not said at what weight the Aliens failed, therefore, we do not know if they are failing at a strength that is significantly lower than their stated strength. Frankly, if they are failing at 10 pounds less than CCH says they will, I could give a rat's ass. If they are failing at 1000 pounds, then I am going to return my Aliens to REI. Statistics aside, CCH is not handling this too well and I hope to see a recall.

CCH should look to Kryponite locks.

The p-value for this test indicates that there is on the order of only 1 chance in 10 million that 33.3% (or more) of the 9 cams tested would have failed at less than there rated strength if the population of cams from which the sample were drawn had a failure percentage of 0.135%.

Is that better or worse?

Jay

I do believe that it's extremely important to note that Paul did not state an exact number of failures, but was clear that 3 were failed brazes... According to CCH's own comments, the wires would fail first, which begs a question about the COMPLETE TEST RESULTS.

Frankly, if they are failing at 10 pounds less than CCH says they will, I could give a rat's ass.

When you're cutting the checks you get to say what's what. That's what both google and usenet look like. Deal with it.

DMT

You should give more than a rat's ass. When part of an object must stand up to a certain weight, a factor of safety is used. Take the simple example of a car's axle. The designer of the axle will calculate the maximum force possible on the axle--this force will likely be much higher than any loads actually encountered. It will take into account something along the lines of the fattest passengers possible, loaded fully with bricks, and doing some sort of landing from high up in the air. For a factor of safety of 2, this force is then multiplied by 2, and the axle must be built to withstand that much force. Most commercial mechanical structures are built to a factor of safety of 2-3. The purpose of the factor of safety is to account for the material behaving abnormally--which can happen occasionally. (Airplanes have a factor of safety just higher than 1, because the materials have been incredibly well-studied in an effort to reduce weight.) For something like a cam it's pretty safe to assume a factor of safety of 2 or higher. For a cam rated at 15 kN (similar to the aliens) with a factor of safety of 2, it should not fail at lower than 30 kn for the majority of the samples (99.9%). By this method of safety, the 1 cam in 1000 that fails below 30 kN will nearly always fail at a slightly lower force, much higher than the rated strength.

To have 1/3 of the cams fail below the rated strength, even if by only 10 lbs, is a huge cause for concern.

...and to dingus, no I'm not writing the checks. But you are trying to convince me, the reader, of your opinion. You want me to view you as intelligent, informative, and correct. So really, it's almost the same thing. You made it complicated and confusing, so I stopped reading your post before I really knew what you were trying to say. I was just giving you a tip to make your post more persuasive. That is what you are trying to do, right? It seems that some others (who had already seen your letters or had the diligence to read the entire thing) really value your input on this topic. It'd do a better job if it was easy on the eyes. Just trying to help you out, man.

There is a lot of speculation in this thread and very very few facts.

Normally, in a companys plan for crisis, you minimise the risk for misleading information by chanelling the responsibility for all external information to a group or one single person. That group/person makes a press statement based on facts and makes sure not to speculate. You do NOT make any statement on a site like this there everyone and everybody can comment and speculate.

Living on another continent I have absolutely no knowledge about Mgear and Paul. Like another writer already has commented, we do not even know for sure that this post is from Mgear! Several has also mentioned that test methods (even at independent institutes) can mess things up severely - that´s why a press statement almost always say that a thourogh investigation is needed.

It might very well be Mgear, since they are in fact saying that CCH is taking this diligently. So there is no absolutely need to flame CCH yet. If I were CCH I would however be asking quite angry question why they were not invited to a joint statement.

Wait for facts - preferably published somethere where the source has been checked. Until when - don´t speculate, so that those who really want facts don´t have to dig through pages of posts from people who don´t know about the case.

Please note that I have only had time to read side 1,2 and 6, so there might be important info that I am missing.

Kudos to Paul and Mountain Gear. It's reassuring that the retailer is looking out after their customers.

Actually, at this point we have quite a few facts in hand.

So I would encourage you and others who have just dropped by and skimmed the thread to please refrain from posting until and unless you have actually read it all...

Boy, you sure can pull a lot out of your ass. That's complete nonsense.

Readers who aren't willing to put in a little effort simply cannot be reached, if you have something *interesting* to say - something that is in any way divergent from the norm. As a writer, you're best ignoring those folks. Seems like everything worked out just right.

You should give more than a rat's ass. When part of an object must stand up to a certain weight, a factor of safety is used.

For something like a cam it's pretty safe to assume a factor of safety of 2 or higher

Actually, at this point we have quite a few facts in hand.

Well, now I have read all in THIS post and there are still very, very, very few facts.