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Category: dealership effect

JDPower Quality Ranking and Statistical significance

Posted in average quality, confirmation bias, dealership effect, JD Power, Lexus, margin of error, Posts, quality survey, ranking, selection bias, statistical significance, and Toyota

…is JDPower more reliable than Republican pollsters?…
JDPower’s latest quality survey reports a gradual (but over time substantial) improvement in vehicles sold in the US, averaging 126 customer-reported defects per 100 vehicles, versus 216 for 2007. That recent vehicles are better than those of a decade ago matches casual observation of new and used cars. But JDPowers also reports numbers by brand, resulting in a ranking widely reported by the media and (when the rank is high) echoed in advertising. (See for example the Feb 13 story in Automotive News.