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      01-12-2014, 10:57 AM   #1890
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Drives: e90 M3
Join Date: Sep 2013
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Originally Posted by catpat8000 View Post
I wouldn't be so quick to draw the same conclusion (2011 being discouraging) for two reasons.

First, because most 2011 cars were built in 2010 and likely had the old bearings.

Second because the data sample, while a good start, is still too small. Imagine, as an exercise, that we had only one sample: a 2012 car. Would we be justified in saying that only 2012 model years had problems? Or that the bearing changes made things worse after 2011? Nope, in reality the data size is just too small. So you see how small data sets can be extremely vulnerable to noise swings.

What we all ought to keep doing is to funnel all reports of bad engines to SFP who can keep the canonical database and hopefully with more time, we will see more patterns as the data gets larger.

If you have an engine fault, send it to SFP!

Fair enough, I just thought maybe there is something hidden deep down in the data we could glean from this. For instance, just looking at the failure data, there is an obvious U-shape at year 1, 4 and prolly 7 had production gone that far.

Even if we assume most of the 2011 failures had the older bearings, it still doesn't explain the 2009/10 trough as those productions also had older bearings.