[PRCo] Re: Riding continues to rise?

[Joshua Dunfield]

2008/12/16 Schneider Fred <fwschneider at comcast.net>:
> Dallas claims that their riding is continuing to rise even though gas
> prices are falling.   Is it?   Well, it is if you compare it to the
> right month in the past.   If you compare November 2008 to November
> 2007, which was lower, then riding is still going up.

That's a perfectly reasonable way of accounting for seasonal variation
in ridership.

> But when you compare a sequence of months in a row, ...

Would you compare a sequence of days in a row?  No, because every
Saturday (and again on Sunday) ridership would collapse, only to
explode the following Monday.

I think the number you really want is % increase of Nov 2008 over Nov
2007 vs. the % increase of Oct 2008 over Oct 2007, etc.  That factors
out seasonal variation and would give real information about the
ridership trend.

-j.