Quote:
Originally Posted by cfg83
I compared the same number of tanks before/after the skirts were added :...
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Quote:
Originally Posted by cfg83
Dividing the After MPG by the Before MPG I get :
44.05 MPG / 42.17 MPG = 1.04458 => 4.45% MPG gain
However, I am not going to claim a 4.45% gain. There's just too many other possible factors. If I delete the two worst (sub 40 MPG) tanks of the 7 "before" tanks I get 43.46 MPG :
44.05 MPG / 43.46 MPG = 1.0136 => 1.36% MPG gain
Because of the above, I will only *claim* a 1.36% gain.
CarloSW2
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I want to jump in so you can get another opinion on that unusual math
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You want to effect both sides of that mileage equation so the standard deviation is the same, compare apples to apples.
If you take the highest and lowest (highest sigma) off of the before
and after tanks, then you come up with something like this:
After skirts: ((44.24+42.3+43.11+45.35+45.25)/5) = 44.05 (left off 45.94 and 42.17)
Before skirts: ((44.57+44.52+42.21+41.01+39.13)/5) = 42.288 (left off 45.01 and 38.71)
((44.05-42.288)/44.05)*100 = 4.00%+
Just don't want you to be short changing yourself, because you were artificially increasing the before tanks without doing anything to your after.
