So I'm working towards my Six Sigma Greenbelt certification. I decided to perform a regression test using my mileage chart. Below is what I got from Minitab. There are some outliers in the cooler temperatures, but all in all I'm pretty confident that there is a direct correlation between average temperature and mileage. [attachmentid=8330]
Ahhh, polynomial regression with confidence intervals! Way to go, cousin Tony. But with temperatures based on oF, I am sure you can appreciate how this equation could 'blow up' at more extreme temperatures (esp. negative ones).
That would support my anecdotal evidence. Anything below 65deg and my milage starts to drop significantly. Above 80deg and I begin to have the ability to see 50+mpg using the same speeds and routes.
I'm thinking that those outliers might be contributed to things such as highway driving versus city driving or even heater usage. Unfortunately for this example, I did not keep data on those items.
<div class='quotetop'>QUOTE(TonyPSchaefer @ May 25 2007, 08:29 AM) [snapback]449719[/snapback]</div> What is your average trip distance? My experience has been that longer distances and higher speeds reduce the temperature penalty. Bob Wilson
<div class='quotetop'>QUOTE(donee @ May 26 2007, 08:36 AM) [snapback]450362[/snapback]</div> I'm not going to minimize the possibility of interconnected variables. I simply did not keep records on the dry-ness of each day and humidity and barometric pressure. There is one data point in particular in which there were something like 7 rainy days of the 11 for that tank. The mileage is bad for that temperature. <div class='quotetop'>QUOTE(berylrb @ May 26 2007, 11:35 AM) [snapback]450428[/snapback]</div> It occurred to me a couple years back that my chart would be much more accurate if I tracked mileage on a daily basis. Then reality/life/sanity hit me. So I decided to continue simply taking records when I refilled. <div class='quotetop'>QUOTE(bwilson4web @ May 26 2007, 10:47 PM) [snapback]450647[/snapback]</div> It seems true that on long distance trips at highway speeds, the impact of ambient temperature is reduced. I can see that when driving from the north side to the south side of Chicago. My average trip is 20 miles one-way to work, taking approximately one hour.
<div class='quotetop'>QUOTE(TonyPSchaefer @ May 26 2007, 11:56 PM) [snapback]450684[/snapback]</div> Wait!! You've been to the south side of Chicago, like south of Madison Ave., like south of US Cellular Field? I've seen no flares go up in the past couple of years . Wayne Who is currently relaxing in beautiful Estes Park, CO.
