Comments on: Driving habits and gas prices shift into reverse

By: Miles driven vs. the price of gas

Miles driven vs. the price of gas — Wed, 26 May 2010 19:24:43 +0000

[...] Via Flowing Data. [...]

By: John W. Palmer

John W. Palmer — Sun, 16 May 2010 20:30:16 +0000

I’d love to see the overlay of this combined with the mileage of the average car on the road, too. Seems like that might be a pending factor, too.

By: Jonathan Nye

Jonathan Nye — Wed, 12 May 2010 13:58:37 +0000

@Ross: Thanks, that’s very interesting.

By: Ross

Ross — Wed, 12 May 2010 03:19:42 +0000

Jonathan: this sort of thing is called a parametric curve. If p(t) is the price of gas as a function of time and d(t) is the per capita distance travelled as a function of time, then this is the curve given by
x=d(t)
y=p(t)
If the equations of d(t) and p(t) were simple enough, it might be possible to come up with an implicit equation for the curve (like the equation x^2+y^2=1 is the equation for a circle). That is unlikely to be the case here, but it doesn’t really matter: a lot of information, like the slope of the graph at a given point, can be found just from the parametric equations with a little first-year calculus.

By: Jonathan Nye

Jonathan Nye — Tue, 11 May 2010 20:53:28 +0000

For you math folks, is there a way to describe this non-function mathematically?

By: Jonathan Nye

Jonathan Nye — Tue, 11 May 2010 20:50:52 +0000

And an great opportunity for the data-obsessed to re-ponder those pesky differences between ‘fewer’ and ‘less’!
http://grammar.quickanddirtyti.....fewer.aspx

By: ezuall

ezuall — Tue, 11 May 2010 19:13:06 +0000

Simple and very intelligent. I don’t know anything about the legitimacy of the data but the method is pretty awesome.

By: Mark

Mark — Tue, 11 May 2010 17:54:38 +0000

“Amazing” what happens when you turn a standard-interval variable like time into a function.. or vice-versa, turn your dependent variables into standard-intervals..

By: Ken

Ken — Tue, 11 May 2010 17:22:59 +0000

It would be interesting to compare a graph like this with a similar one showing miles per registered vehicles or car owners, or something similar. Those might tell a different story.