It is hard for anyone who is trained in Lean Six Sigma to understand the latest Toyota recall. Toyota wrote the book on quality after all. Really. Look up The Toyota Way.
Six sigma is a process improvement methodology that focuses on measuring defects and variation. Six sigmas are six standard deviations from the mean (you will have to go back to your grade 9 math text books to read about this.) And this measure of variation translates into 3.4 defects per million.
You might get 99% average in high school and 99% on your SATs and you get into Harvard, Western Ontario and Duke. But if you manufacture one million widgets that are perfect 99% of the time, you are less than 4 sigma and there are still 10000 duds in that million. You shouldn’t even get into community college with 4 sigma brains.
So imagine getting your process down to about 3 defects per million? That sounds pretty good? That’s pretty damn dear perfect. 99.99966%.
By contrast Ford estimated the defect rate on the Explorere/Firestone tires at 241 tires per million (5 sigma) and about 250 people actually died from those tires and rollovers.
But apparently six sigma it’s not good enough because Toyota is recalling over a million cars for fewer than 3 reported stalling defects.
Truth is Toyota’s reputation got burned recently so it’s good that they are getting ahead of this one. But leave them alone because they are still better than anything made by GM, Ford or that other one.
(Please note I drive a Toyota, shown below.)