jamesf99
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 p.6 #13 · 5DII failures on LL Antarctic trip | |
Steve Spencer wrote:
Sorry, but as a scientist you should know better. What comparison are you suggesting is statistically significant? And what statistical test would you use to determine this significance? Unless you define a specific test you are making and you can point to a statistical test you used and the parameters from that test, then you should not be saying that it is statistically significant. IMO, it is bad science to suggest that something is statistically significant without doing the actual test of that significance.
As a scientist who teaches statistics to PhD students,
Uh oh....Now here is a point that I say is conclusively, unequivocally, and absolutely insignificant. 
Sorry, but I spent enough years in graduate school with fellow PhD students and masters degree candidates, and some of the worst instructors an Ivy league school could provide to know that your point is easily "challengable"........
I can say I know of no test that would let one make an inference about statistical significance in this case. If there is such a test I would be happy to have Mark correct me. Part of the problem here is that it is not even clear what is being tested. Is the test whether there are more failures than zero? If that is the test then it is not a matter of statistics, but simply a matter of observation. Yes there were more failures than zero--obviously. Is the test, however, whether there were significantly more failures among the Canons (or specifically among the 5DMKIIs) than among the Nikons or Hasselblads or whatever? Now this question could possibly be addressed with statistics and one wouldn't even need to know confidence intervals. It could be tested with a simply chi-square test, if there were enough observations of Nikon cameras failing. With the current data there just isn't a big enough sample of Nikon cameras to do the comparison. A chi-square test would require more observations of other cameras failing. I don't see a way to test for statistical significance here, and that makes the report here an anecdote. A compelling one, but unless someone makes it clear what comparison they are testing and how they carried out the test, then they should not claim that the reported incidence of failures is statistically significant.
Best wishes, Steve ...Show more →
Of course we don't have all the information and what we do have is mostly - but not all - anecdotal, but 6 out of 26 is bad news. You can spin it anyway you want, and spend 6 weeks designing your test/population/confidence levels, but it's bad news. If you take 26 cameras at random, use them in an ordinary way, and 23% of them fail, you are talking about a serious issue and you don't need to design a complete statistical analysis to know that. No Nikon died under the same circumstances.
EX: 26 new, randomly selected, undamaged Toyota's drive from Boston to NY. 6 die along the way for one reason or another, but in no case were they subjected to improper or even deliberate misuse. Surly you must ask why, but in this case if you want the most basic analysis you could start with "what is the chance your new 5d will go belly up if you look at it wrong"? You may or may not want a larger sample size, but I think we're on to something here.
We don't need a chi-square test, any more regression testing, we need common sense. This shouldn't happen. Period.
Unfortunately, common sense isn't all that common.... M. Twain
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. Not sure if the grip is also weather sealed 
Just saw this service notice: