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Old 07-21-2008, 12:17 PM   #14 (permalink)
pasadena_commut
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Quote:
Originally Posted by Arminius View Post
I may do more experiments once the guilt of wasting all that gas and ruining by mileage by driving without hypermiling wears off.
An interesting, but not convincing, set of observations. They do trend in the desired direction, which is good. However, in terms of experimental design there are two problems. (These are common problems in this sort of test, I'm not singling you out.)

1. The data is limited. The means differ by .37 mpg but that is not much different than the variation within the measurements, so we can't say with much confidence yet if it the measured difference is statistically significant.

2. You knew the state of the car for each test, which opens up the possibility of subconscious changes in driving style which could bias the results. If you do repeat the experiment it would be good if you could have somebody else flip a coin before each run and then open or close holes without telling you which they did. You can determine which it was at the end of the run.

I'm still skeptical - it doesn't seem right that the tiny amount of air coming out of those two small holes could significantly affect the large and continuously generated volume of low pressure air behind the car.
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