Nice job in attempting to get reliable and real-world data for gas consumption! As MetroMPG has pointed out in the past, this is not trivial. My coast-down numbers also have made me take a cautious approach.
Quote:
Originally Posted by jimepting
....5. Gather multiple data. In a rigorous statistical sense, it is probably impractical to gather enough data on a course of realistic length to meet standards of statistical significance. Having rusty statistical skills, I don’t actually know how to approach the problem of statistical significance. It is noted that others have felt that 3 runs were adequate for an FE baseline. I chose to make 6 runs, just to be a bit more assured of consistency.....
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I don't know if this will help much, but at work we use MiniTab for statistical analysis on occasion, and a sampling of 3 or even 6, at least statistically speaking is not much to work with for a sample size.
In the past, some of our company statisticians have promoted the use of at least 30 samples just to get a rough idea on how well the manufacturing process is working, and how much standard deviation the data has.
I try to keep a gage history of at least 20 samples and perform either 2 or 3 sigma standard deviations on the data set to see how a particular gage is performing historically.
When doing coast-down testing last fall/winter, I accumulated around 40 or 50 runs before getting enough data to really start making predictions on how the barometric pressure and temperature affect the coast down times. I still have a ways to go on this, and having the tail extension will change the aero enough to setup the chance for more runs this fall/winter.
Hope this helps.
Jim.