The devil is in the details!

Mark Wells brings up a good point in his comment to my "Traffic" post. However, as the title of this post says "The devil is in the details!"

I have the Traffic Study sitting in front of me. It does say that the 9,212 comes from the ITE "weekday trip generation average rates". However, this is not the "average" number presented by Mr. Kim for the low-rise condos. The technical, statistically correct meanings are getting lost in semantics here.

During the meeting Mr. Kim presented the 9,212 as the product of the ITE trip generation formula. This is the true and correct meaning. The 12,252 trips came not from the ITE manual, but rather from a straight averaging of the data points. You know, add all the trips together and divide by the number of data points? This produces a straight line on the graph. As we all know from common sense, traffic density is not a straight line. Certain times of the day it is very tight and other times there is not another car in sight.

This is what makes straight averaging inaccurate and misleading. To the reader unfamiliar with this technical language, the words "average rates" can easily be confused with "average trips". But the "average rate" is used to multiply against another number to get the "hard" number of actual trips. "Average trips" is the final hard number with no flexibility. Then you have the scenario I outlined in my previous post.

As to who was exerting the pressure on Mr. Kim, I would like to reserve that opinion for now since it is merely speculation. Nonetheless, it should have been obvious to everyone that he was nervous as hell and venturing into unfamiliar territory. This could have come only from his being forced to use data LA DOT does not normally use in their regular course of business. My question is why are they being pressured to do this?