Quote:
Originally Posted by Perfectlap
Those stats are for failures tracked by Porsche through their engine replacement program. They leave out the mountain of cars Porsche had no dealing with with post warranty where owners were entirely on their own. There are far too many variables left out to put any weight behind the percentages in the Porsche numbers beyond that single bearing cars fail far more often than dual row. Its pure guessing to attempt to decipher the technical cause based on the imprecise degree of separation. WWII.
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I disagree with your comments that one can't "put any weight behind the percentages" and "it's pure guessing" tu use the Porsche numbers because statistics show that the uncertainties between Porsche reported failure rates and actual ones are likely very small to make meaningful differences.
For example, if Porsche used just one-fourth of all actual dual row failures when calculating its reported rate, which is very likely the case, then one can say with 95% certainty that the actual failure rate for all dual row cars lies somewhere between 0.9% and 1.1%.
Moreover, if Porsche used just one-sixth of all actual single row failures when calculating its rate, which is even more likely the case, one can say with 95% confidence that the actual rate of single row failures lies somewhere between 7.6% and 8.4%.
These differences - 1% versus 0.9% to 1.1% and 8% versus 7.6% to 8.4% - are just too small to disregard the reported Porsche numbers.