Math error with the running average - Fuelly Forums

Click here to see important news regarding the aCar App

Go Back   Fuelly Forums > Fuelly Community Support > Fuelly Web Support and Community News
Today's Posts Search Click Here to Login
Reply
 
Thread Tools Display Modes
 
Old 06-25-2011, 03:28 PM   #1
Member
 
Join Date: Apr 2011
Posts: 71
Country: United States
Location: Charlotte, NC
Math error with the running average

Is there a math error with the running average? I understand that it uses the last 10 fill ups, but I have 8 fill ups total (all since April) and my running average is 20.1, but my regular average is 20.3

What happened to the other 0.2 MPG?
__________________

Ciderbarrel is offline   Reply With Quote
Old 06-26-2011, 12:32 AM   #2
pb
Senior Member
 
Join Date: Jul 2008
Posts: 1,588
Country: United States
Location: Corvallis, OR
The two stats use slightly different methods of calculation. The running average takes all of the averages that have been calculated for your fuel-ups so far and averages them. Your total average on your vehicle profile page takes total miles / total gallons to reach that figure.

We've found that for your total average, using this method of calculation is slightly more accurate because it includes partial fuel-ups. However, for short time periods, using the average of calculated averages tends to work out better specifically because it doesn't include partial tanks.

So it looks confusing in your situation since the two should match, but the different methods of calculating things lead to different results. And we try to use best method of calculating for the type of stat.
__________________

pb is offline   Reply With Quote
Old 06-26-2011, 08:07 AM   #3
Member
 
Join Date: Apr 2011
Posts: 71
Country: United States
Location: Charlotte, NC
Ahh, ok. I got it.

I did the math by hand for the "average" average and got basically the same thing. 20.06 rounded up to 20.1 (160.48 total MPG averages / 8 fill ups) vs my 2092.2 miles / 102.98 gallons for 20.31 rounded down to 20.3.

So, if I have this right, regular MPG average is all fillups, running MPG average is average MPG of last 10 fillups, except for partials, right?
Ciderbarrel is offline   Reply With Quote
Old 06-26-2011, 10:35 AM   #4
pb
Senior Member
 
Join Date: Jul 2008
Posts: 1,588
Country: United States
Location: Corvallis, OR
Yep, that's it—almost exactly. When you add a partial tank, Fuelly doesn't calculate an individual MPG for that tank or the next one. So even if that tank after a partial is full, it won't have a calculated MPG. That means it won't be included in the Running Average MPG on your dashboard.

So just to make it completely clear I'd say that running MPG average is the average MPG of the last 10 fuel-ups, excluding those without a calculated MPG.
pb is offline   Reply With Quote
Old 12-20-2013, 10:45 PM   #5
Registered Member
 
Join Date: May 2009
Posts: 7
Country: United States
Is there a way to suppress running MPG as the primary reporting number. It is immaterial to me, I want only my average based on all gas and mileage. It is annoying that I have to click through to get this.
fbobberts is offline   Reply With Quote
Reply


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 04:17 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.