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Comment by Kylekramer | Hacker News Reader

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Kylekramer

So a problem with precision and judgment, but not integrity?

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and integrity:

> NHTSA does not rate vehicles beyond 5 stars and does not rank or order vehicles within the star rating categories.

So the following statement is flat-out untrue:

> SETS NEW NHTSA VEHICLE SAFETY SCORE RECORD

If NHTSA does not rate vehicles beyond 5 stars, the maximum safety score is 5 and thus 5.4 is irrelevant

I think if the headline was "sets new vehicle safety score record", dropping the NHTSA acronym, then it would be fine.

The Tesla blog post makes it abundantly clear that the 5.4 is the report the manufacturer receives (not the issued rating which is capped at 5). Why does it stop at 5 if you can still die in those cars?

I don't think it does make that clear. It says "safety levels better than 5 stars are captured in the overall Vehicle Safety Score (VSS) provided to manufacturers" but the VSS value for the Tesla was 0.43 according to the blog post. So where did the 5.4 come from? Extrapolation?

You're right - they didn't make it abundantly clear that the VSS report was 0.43. Regardless, the conversion they made isn't insane when you look at the other VS scores. Plus - watch the videos of other 5 star rated vehicle versus the Model S. It's like the comparison between a 1980s car and one from 2013.

NHTSA Six Stars: The car is a mobile fortress.

All I meant was that if 5 stars isn't perfect why is that the scale they're using? Obviously the range of what a 5 star rating represents could mean the difference between life and death in a serious collision.

I am clearly agreeing with you. A mobile fortress is far more perfect in terms of safety than any consumer car on the road.

It might not move fast, but you need military-grade hardware or construction equipment to make a dent.

NHTSA doesn't PUBLISH ratings above 5 stars. Regardless, the 5.4 IS relevant.

The fact that the NHTSA formula gives a score of 5.4 doesn't mean that NHTSA recognizes the car as superior to those with a technical score of 5.3. To put it differently, if a class gives a grade of A,B,C,D,or F, having a numeric score of 99 versus 98 is somewhat irrelevant if the ultimate grade is A in both cases.

If they really did want to make a distinction, they'd introduce a new scoring metric that does allow for those differences

If you were in school and had a bet with your roommate about final grades, you wouldn't call off the bet as a draw if you both got A's but you got a higher numeric score than he.

If you had a bet with your roommate about final grades, you would look at the transcript at the end of the semester. And that transcript most likely says A for both of you, so it would be a draw.

I'd jump on the web and see the grades posted by the professor on the course website actually. I always got numeric grades at the end of the semester unless I waited long enough that the course website was nuked, or unless that professor was lazy.

You could also just go ask the professor at their office for your grade, but using their site is easier.

For a bet like that, it doesn't matter if the score difference results from random chance and not any underlying difference in skill or ability. The NHTSA is in the business of assessing car safety though, and it makes little sense for tnem to rank cars within a category if they don't think the difference is actually meaningful.

But having a numeric score of 59 versus 9 is relevant, despite them both being F. Likewise, 89 versus 90. NHTSA can do whatever they want; I can say it is just a silly metric that is about as good as gaming reviews, as another comment points out. A 5.4 score is still relevant; why would they throw away precision?

OTOH, the whole rating system is about taking real tests and progressively throwing away levels of precision. Like combining front and rear and side impact into a single score.

The NHTSA probably doesn't think that a safety score of 5.3 versus 5.4 has any sort of meaning. If the set of accidents under which you would survive unscathed in a car with score 5.4 but would be injured in a car with score 5.3 has measure 0 (or negligible), then there is no real difference in terms of safety (even if the scores are different)

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