Re: Freight Car Distribution on smaller RRs

Dave Nelson
 

Mike Brock wrote:

Yes. Modeling the UP on Sherman Hill over a three hour time period
with its 35 frt trains doesn't match well with, for example, a yr's
worth of data.
I have never said a year long sample was required. I have always suggested
that a minimum of 1000 foreign road boxcars be counted and always felt more
comfortable w/ something closer to 1500. On some secondary line, seeing
1000 foreign road boxcars might take a rather long time, tho I still think a
year is way too long. On Sherman Hill, I suspect 1000 foreign road cars
would be seen in days.

Moving on, Mike, you continue to toss out the argument that since your data
has 1 train w/ a large number of SP boxcars in it that the distribution
hyposthesis isn't very useful. I have countered numerous times that 1) one
train does not make a sample and 2) the distribution hypothesis has nothing
whatsoever to say about the composition of a single train. I will fall
back, once again, on my Yoplait Yogurt in the shopping car example: I do not
purchase Yoplait at regular prices (tho my daughter may slip in one or two
when I'm not looking); However when they are half off I but a whole lot of
them. The composition of my carts therefore varies considerably when
examined individually but the average number of yoplaits I buy over numerous
trips is probably pretty constant over time if enough trips are recorded and
analyzed.

What does this do for the MWR car? Well, nothing. The 1953 ORER shows 100
MWR box cars. For me to have one MWR box car
and match the N-G data base, I would need 7400 box cars. Anyone think I'll
make it? Incidentally, using the 500 box car data base, I
could not use a box car if a RR had less than 1480 box cars. Whew. SP&S
barely makes it in. Tucson, Cornelia, and Gila Bend with
their 3 cars missed the cut along with the Montana, Wyoming &
Southern...which might be over represented due to their close proximity
to the UP except for the fact that they had no box cars.
That is all correct. Which is why Hendrickson was hyperventilating earlier
today about absurdites. Fortunately, yours is a hobby, not a job, so if you
want to enjoy a MWR car, go ahead. Just keep it out of sight when Richard
visits. 8-) Or leave it over on the shelf in a nice display, where it
probably belongs all of the time.

Let me return to discuss a point I mentioned earlier today, which is,
really, which hobby: The problems most often raised on this subject are the
problems of (physical) model railroads, not of the distribution hypothesis
itself (that does have objections but they're mentioned less often). I
operate a (virtual) model railroad and can have many hundreds of 60, 70, 80
car consists composed, in total, of thousands of individual cars. My
constraint is the limited availablity of models, not the number of them (and
certainly not the cost... As they are all free), and that makes for a very
big difference in the utility of the distribution hypothesis.

Dave Nelson

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