Rear wheel skirts

[omgwtfbyobbq]

What you seem to be talking about is the potential impact of different things we are unable to control for. I think that the SD is already representative of our controls compared to what we can't control. For instance, if I were to try to pick up a .5mpg difference based on my gaslog for White Bread, I would need thousands of runs because I don't control for weather, route, driving habits, or traffic and my tanks have at least a few mpg difference between each. I figure the average speed could be controlled fairly well since the SG can report average speed, so as long as those are within the same SD the mpg figures are, a test should be o.k. Wind gusts are already incorporated into the average wind speed, but I suppose we could see something come out of nowhere, but it would show up in the data. I think this is why the line ...gives an 80 chance that an 0.05 level test of significance... is present, since there can be a convergence of unlikely events that could lead to something appearing helpful when it's not, although, this is fairly unlikely. I think that the more we test, the more unlikely it becomes.