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Crash Tests Show Not All Minivans Are Created Equal

Discussion in 'Mopar News' started by Hemidakota, Aug 16, 2018.

  1. GasAxe

    GasAxe Well-Known Member

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    I agree, but there is money to be made in the non-binding testing, that's why they do it. OEM's could snub the tests since they aren't binding, but the buying public now expects automakers to build cars to arbitrary standards that aren't even made when the vehicles are developed!

    It's not all a terrible game of increased expectations though. Automakers tout results when they are in their favor to promote sales. The majority of consumers continue to willingly pay increased costs for the safer, more efficient vehicles. Progress through Capitalism!:D
     
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  2. Erik Latranyi

    Erik Latranyi Allpar Legacy

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    Don't forget, the media loves these Insurance Institute studies, especially when there is bad news about a popular vehicle.
     
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  3. Ryan

    Ryan Moderator
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    If they didn’t, that makes their data seem potentially flawed. Wouldn’t that be something they needed to do on every car model, anyway, instead of making generalized assumptions about every make and model from a test on just one kind of vehicle?
     
  4. Zagnut27

    Zagnut27 Jeepaholic

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    Yes, they did do that. I contacted a source at IIHS and he gave me some insightful info on how they do their testing, so on and so forth. I’ll post it later after I’ve had time to read all of it...hard to see it on my cellphone.
     
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  5. freshforged

    freshforged Well-Known Member

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    $$$
     
  6. Zagnut27

    Zagnut27 Jeepaholic

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    Joking? No. There are instances where extremely small sample sizes, including one, have to be used, simply because it is cost prohibitive, unethical, or there simply are none to be used for testing in a lab. We do it in healthcare when examining individuals with extremely rare conditions where you are testing new therapy without the benefit of additional human subjects. But other human subjects exist in the world, but they are unable to participate in the research for various reasons. When comparing them to individuals in real-world testing, those subjects then become part of your sample size. It is a complex process, but yes it can be done. In this case, one sample model is supposedly being used, and the results of that testing are compared with real-world data. So yes, your initial sample size is of less relevance if you are also able to incorporate real-world testing as well.
     
    #86 Zagnut27, Aug 21, 2018
    Last edited: Aug 21, 2018
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  7. Zagnut27

    Zagnut27 Jeepaholic

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    I sent an email to a gentleman who works at IIHS, and he kindly forwarded it to another gentleman who was able to answer my questions. Below is his reply to my email:

    "The repeatability of crash tests has been confirmed by research and many years of testing. IIHS research in the 1990s demonstrated the repeatability of the frontal offset crash test. See attached.

    Research has also shown that front and side crash test results from IIHS predict real-world safety outcomes –

    http://www.iihs.org/iihs/sr/statusreport/article/39/2/1

    http://www.iihs.org/iihs/sr/statusreport/article/45/13/2

    Detailed technical protocols published by IIHS allow automakers and other independent labs around the world to duplicate our tests. An example is the IIHS crash test verification program open to automakers whose vehicles have performed well in IIHS tests for many years. When those good-performing vehicles are redesigned, the automakers submit video, structural measurements and dummy data from IIHS-designed crash tests that were conducted in the automakers’ own labs. IIHS engineers review the data and assign a rating. IIHS periodically conducts random audit tests of these vehicles to verify results. While there can be some variability from vehicle to vehicle for individual test parameters like dummy injury measures or structural performance, the differences are usually small and don’t affect the vehicle’s overall rating.

    Based on years of testing and decades of working with other researchers and the automakers, we know that multiple tests of the same vehicle model in any lab around the world using IIHS protocols results in the same rating."

    He also included a pdf of a research article entitled, "Repeatability of offset frontal crash tests" by Susan L Meyerson. I'll try to post it here as a pdf. I did find an article from the NHTSB which demonstrates the repeatability of the research done by IIHS, and I'll post that link below. They detail why the use of 1 vehicle is acceptable because the degree of variation between representative models of the same vehicle is quite small, and not likely to change the test results dramatically.

    https://www-esv.nhtsa.dot.gov/Proceedings/23/files/23ESV-000079.PDF
     

    Attached Files:

  8. Erik Latranyi

    Erik Latranyi Allpar Legacy

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    Thank you @Zagnut27 ! This should silence the keyboard warriors who spout off without knowing the facts behind things in their attempt to minimize bad news. Not that the Pacifica tested poorly at all! But they still insisted the methods were flawed.

    I alluded to this and was immediately attacked.

    Yes, many industries use correlation to minimize sample sizes. It is a proven methodology if you do it right.

    The auto industry would not give these tests so much attention if they were as flawed as many here tried to claim. You do not spend millions to redesign a vehicle for a crash test you think is flawed.....and that has happened many times.
     
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  9. valiant67

    valiant67 ...

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    @Zagnut27 went above and beyond, contacting them directly. Way to go!
    As I mentioned earlier, the IIHS has so much information about this test, the history, the methodology, etc. all online for anyone to read.
    They aren't a bunch of hillbillies randomly deciding to crash vehicles into things.
     
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  10. Erik Latranyi

    Erik Latranyi Allpar Legacy

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    [​IMG]
     
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  11. Zagnut27

    Zagnut27 Jeepaholic

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    My thinking centered around the fact that they are able to compare to real world results, and also in how the results from their testing are conveyed to the public...as in giving ratings of good, marginal, etc. Those are not results that convey a degree of accuracy as say 90% chance of this or that occurring. It allows some wiggle room in the confidence of the results. It turns out, I was right. When comparing the results of two of the same model, there are some variations but usually not enough to change a rating or if so, then only one. Which makes sense because there are so many variables involved in real-world crashes that it would be impossible to be too exact when trying to predict how a vehicle will perform in. So the take away message for the consumer is, the higher the stars, the better your chance of not getting hurt, and that is definitely confirmed by the research.

    I have a tendency to explain things in an abstract way because I’m used to dealing with issues that have tons of variables. It gets me into trouble sometimes when I’m trying to explain things to people...they might be looking for a concrete, black and white answer, and I end up going off on tangents. Lol. Probably like now. :p

    If I’ve learned one thing through obtaining 3 degrees, it’s how to perform research...I can research like there’s no tomorrow! Lol. But when in doubt, go to the source and contact a SME (subject matter expert).

    Absolutely, they are very transparent with their methodology. They want people to know what they’re doing and how they’re doing it. Because they want you to be able to reproduce their testing...which is the basis of effective scientific research. If your results aren’t reproducible, then they’re meaningless. And they’ve got a lot of well-educated, intelligent people working for them...and they’re apparently very happy to answer questions about how they do their work. I did mention I was a member of Allpar, so maybe that’s why. :D

    Here’s the background for their employees: (The only dummies there are of the crash test variety :D)

    The Institute's Vehicle Research Center and other crash testing facilities are staffed mainly by technicians and engineers. People with some training in electronics, computers, photography, auto mechanics or fabrication (machine tools and welding) prepare vehicles for testing, calibrate and install sensors, build test fixtures, calibrate and maintain test dummies and film crash tests. Research engineers and more senior employees have degrees in mechanical engineering, and some have completed coursework in biomechanics or biomedical engineering. Courses in these areas are offered at many large engineering schools, including the University of Michigan, Wayne State University, Ohio State University, George Washington University, University of Virginia and University of California, San Diego.
     
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  12. GasAxe

    GasAxe Well-Known Member

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    This has been a good example of validity versus relevance and how to come to a sound conclusion when on a budget.
     
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  13. svevar

    svevar Well-Known Member

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