Hi Jason:
___Although I haven’t had a stat class in over 15 years and my last semester long one was well before that, a reliable statistic at a given 95, 97.5, 99% etc. confidence with a given sample size relative to a given - total population is a first year type calculation. I have seen it in the past but I do not know what it is anymore. A google on 95% confidence, sample size, and total population should lead you to what you are looking for. If you do not find it, pose the question to your stat teacher like this:
What is the confidence level of a given Prius II owner to achieve 47.9 mpg with a sample size of 154 vs. a total population of 88,416 (total 04 and 05 sales through March 2005)?
___Make sure you mention that the FE posted in terms of tank over tank is by a population that may or may not be representative of the general population as a whole given the caveats of hypermiler tank uploads vs. non-hypermiler tank uploads. See below. She may know of a way to remove some of our lmpg’s as well as the low balls from the calculations to give a new member/reader a real sense of what their average may or may not be from a given hybrid.
___The problem as I see it is that many of the GH members - tank over tanks are not complete. You have a general idea as to what an average FE may be for a given automobile but with 25% or more of the tanks posted coming from hypermilers, it would tend to scare off the lesser FE receiving members from posting lesser tanks. This leads to a higher average then what the general population may in fact receive that cannot be adjusted for with statistics. Maybe a psychologist would need to be contacted to remedy the skew us hypermilers instill into the overall data
___Just last night I removed the Overrides from the Hypermiler list because of anomalies I was beginning to see. It is very easy to upload “I get 48 mpg from such and such a vehicle” vs. posting actual tanks from receipts and the odometer and the ease at which to stretch the truth a bit just once is a lot easier then once, twice, four times a month if you know what I mean. IIRC, you do not use the Overrides in a particular automobile type or overall stat’s, right?
___Finally, I do wish you would increase the digits in the FE calculations just a bit although I dread re-editing all of the tanks posted to date
Every gas station I have filled up at in the last 4 years has a xx.xxx gallons or down to (1/1000) of a gallon pumped shown. This being the actual is probably mis-leading of course but I always post it in the notes … The odometer or at least Trip A/B shows down to a tenth. Your Odometer entry w/ no digits to the right of the decimal point is a bit odd imho.
PS: Your new edit mode stinks. It produces edits in a quasi - hypertext mode w/ huge spacing, bolded text in some areas and not in others, weird <font> type code and such … Editing the Hypermile list or even this post is a huge pain in the @$$ because of this
Is there a way to change the Edit mode in my CP somehow? It started just the other day …
___Good Luck
___Wayne R. Gerdes
___
Waynegerdes@earthlink.net
Re: Math & Decimal Accuracy
This entire year, we've never dealt with population size unless it was proportions - this is means.
