Hi Everyone

Here is some info on the distribution of box and auto cars for trains on the U.P. mainline between Laramie and Rawlins in 1938. The data are compiled from three Freight Conductors' Train Books written by conductors Ferguson, Fraley, and Fitz. Ferguson's data are from May and June of 1938, while Fraley's and Fitz's are from September-October of the same year.

In the tables below the information from the train books is compared to national averages based on the January, 1938 ORER. The national values count only box, auto and ventilated cars in interchange service on Class I U.S. roads or their lessees.

The tables show the road initial, the number of box/auto cars in the conductors' books, the percentage these cars represent, and the national percentage. Only roads with 5 or more cars reported in the train books are listed.

Roads in which the percentage of cars tallied from the conductors' books exceeds the national percentage.
Road: Num; Book %; Nat %
SP: 201; 15.1%; 3.3%
CB&Q: 125; 9.4%; 3.0%
NYC: 99; 7.4%; 6.1%
MILW: 83; 6.2%; 4.7%
CNW: 64; 4.8%; 3.2%
WP: 54; 4.1%; 0.4%
GTW: 53; 4.0%; 1.3%
RI: 44; 3.3%; 3.1%
MP: 33; 2.5%; 2.3%
IC: 32; 2.4%; 2.3%
SLSF: 31; 2.3%; 2.0%
PM: 26; 2.0%; 1.5%
DT&I: 21; 1.6%; 0.3%
NKP: 15; 1.1%; 1.0%
T&P: 15; 1.1%; 0.5%
T&NO: 14; 1.1%; 1.0%
CGW: 8; 0.6%; 0.5%
CMO: 7; 0.5%; 0.5%
B&LE: 5; 0.4%; 0.0%

Roads in which the percentage of cars tallied from the conductors' books is less than the national percentage.
Road: Num; Book %; Nat %
PRR: 79; 5.9%; 10.4%
ATSF: 36; 2.7%; 4.9%
MC: 27; 2.0%; 2.5%
B&O: 24; 1.8%; 4.4%
NP: 24; 1.8%; 3.1%
SOUTHERN: 19; 1.4%; 3.6%
WABASH: 18; 1.4%; 1.6%
GN: 15; 1.1%; 3.5%
SOO: 15; 1.1%; 1.4%
ERIE: 13; 1.0%; 1.4%
L&N: 11; 0.8%; 2.2%
C&O: 9; 0.7%; 1.4%
CCC&STL: 7; 0.5%; 1.5%
N&W: 7; 0.5%; 1.0%
D&RGW: 6; 0.5%; 0.6%
M-K-T: 6; 0.5%; 0.6%
DL&W: 5; 0.4%; 1.3%

FWIW the percentage of box/auto cars that were UP is 41% - 935 cars of a total of 2,267. (1,332 cars were used to calculate the Book % in the tables.)

Best wishes,
Larry Ostresh
Laramie, Wyoming

Howdy

Here is an update on the distribution of box and auto cars on the UP between Laramie and Rawlins in 1938, with tables that show the cars classified by the ICC region of the owners. This analysis and my previous comparison of data for specific railroads (# 89886) lead me to conclude that the G-N hypothesis does not work very well for the UP in 1938.

The first table lists the names, abbreviations, and number of box/auto/ventilated cars of the ICC regions. The number of cars is for cars in interchange service on ICC Class 1 railroads and their lessees only and is based on the January 1938 ORER.

ICC Region: Abbrev; ORER N of cars
Central Eastern: CE; 130,863
Central Western: CW; 144,296
Great Lakes: GL; 156,429
New England: NE; 23,947
Northwestern: NW; 126,201
Pocahontas: POC; 18,694
Southern: S; 100,611
Southwestern: SW; 56,970
TOTAL: 758,011

The next table gives the number of cars listed in the three Freight Conductors' Train Books by Fitz, Ferguson, and Fraley, classified by region.

Abbrev: N of train book cars
CE: 145
CW: 1,408
GL: 269
NE: 3
NW: 218
POC: 16
S: 73
SW: 111
TOTAL: 2,243

In addition to the cars shown in the table above, the train books list 5 cars from the CN and 19 others whose reporting marks were illegible or could not be found in the ORER. There are thus a total of 2,243 + 5 + 19 = 2,267 box/auto cars reported in the train books.

Data from these tables may be combined to provide a test of the G-N hypothesis of freight car distribution. My understanding of this hypothesis is that it predicts that the proportions of cars observed in a sample of real trains should approximate the national proportions. However, the home road cars should be removed before comparing the proportions.

In this case, the home road is the UP, part of the CW region. There are 27,624 UP box/auto cars listed in the 1938 ORER and 935 in the conductors' train books, so these should be removed from the appropriate tables. This leaves 116,672 and 473 cars in the CW region for the ORER and train books respectively, with totals of 730,387 and 1,308 cars. Once this is done, the percentages of cars in the ORER and train books are as follows:

Region: ORER, Train books
CE: 17.9%, 11.1%
CW: 16.0%, 36.2%
GL: 21.4%, 20.6%
NE: 3.3%, 0.2%
NW: 17.3%, 16.7%
POC: 2.6%, 1.2%
S: 13.8%, 5.6%
SW: 7.8%, 8.5%
Total: 100.0%, 100.0%

Several of these percentages (GL, NW, and SW) appear very comparable. However, the CE, NE, and S regions are greatly underestimated in the train books while the CW has over twice the representation that it should have.

Another way of comparing the tables is to allocate the 1,308 box/auto cars (2,243-935 UP cars) from the train books according to the ORER distribution and compare the actual and predicted numbers of cars:

Region: Actual; Predicted
CE: 145; 234
CW: 473; 209
GL: 269; 280
NE: 3; 43
NW: 218; 226
POC: 16; 33
S: 73; 180
SW: 111; 102
TOTAL: 1,308; 1,307 (Predicted does not sum to 1,308 because of rounding errors.)

The CW region contains the SP as well as the UP and we have had many discussions over many years on this list about the well-known over-representation of its cars in trains across Wyoming. 201 of the train book cars belong to the SP, whereas it "should" have only 44. This leaves an "excess" of 201-44=157 cars, which arguably should be removed from the 473 train book cars in the CW region. If they were removed, then the CW region would be left with 473-157=316 cars which is still half again as many as the 209 it should have.

So does this data support the G-N hypothesis? In my opinion it doesn't, but I stress that this is just an opinion and nothing more – others may decide it provides fine support, or the data have so many flaws it should be ignored. One flaw, a small sample size, will be ameliorated in the months and years to come: I still have over 120 train books to transcribe for the Laramie-Rawlins run in the late 1930s. With an average of 2,300 cars per book, 450 of them foreign box/autos, eventually the sample size should exceed 50,000 foreign box/autos.

I think I recall Tim Gilbert writing that the G-N hypothesis fits the data well during economic prosperity but does less well during recessions and depressions. The year 1938 was during the Great Depression, of course. The high proportion of home cars (41%) is another indication that companies may be keeping their cars close by. It might be that modelers wishing to have a realistic mix of cars on their trains should pick an era first – or perhaps even a specific year and season, and then check what was happening in the national economy at that time. The choice of the G-N vs. a regional (or any other) model for an accurate freight car composition may well depend on such ephemera.

Best wishes,
Larry Ostresh
Laramie, Wyoming

Larry, does 2,267 box cars on the UP mainline even represent the
traffic of a single typical day? So here we are looking at freight
trains spread over four months... or on any given day, less than
1% of the box cars on the main line are sampled.

What can be learned from this? Nothing, I believe.

Look at it another way -- suppose you had conductors books for the
same time period from three other conductors. Do you think that the
tallies would be the same? I don't -- not one chance in a thousand.
So then, which would be the representative sample? Answer: neither.

If you had ALL of the conductors books for every day for a full
week, now that would be interesting! That would smooth out a lot
of the daily fluctuations. Of course there's seasonal variations,
but that might actually be easy to discern in a large sample.

Tim O'Connor

Tim O'Connor writes:

Larry, does 2,267 box cars on the UP mainline even represent the
traffic of a single typical day? So here we are looking at freight
trains spread over four months... or on any given day, less than
1% of the box cars on the main line are sampled.

What can be learned from this? Nothing, I believe.

On the contrary, I think we know a great deal. We know what UP frt trains looked like. From my conductor's book, we know what 34 trains looked like. Not in a given day, but over about a month. Does this tell us very much about the total traffic over a month? No. OTOH, does knowing that help much with modeling a RR or part of it? No. Modeling frt trains requires information about frt trains and from the conductor's books we know that such trains were not just randomly put together from the available pool of cars...as would be the case if we just used the G-N. So, it all depends upon one's objective.

Look at it another way -- suppose you had conductors books for the
same time period from three other conductors. Do you think that the
tallies would be the same? I don't -- not one chance in a thousand.

Well...not the same but I believe that you would see similar trains. If you had all of the UP conductor's books for a couple of weeks you would discern unique trains consisting of similar consists...some running daily. Even in my 34 trains, it is easy to see similar trains. For example, reefer blocks, lumber trains, tank car trains [ both MTY & loaded from Sinclair ], stock trains, coal trains and even merchandise trains. The cars will be different but there were specific trains running almost daily...Roseville Fruit for example. And, while cars are different, except with merchandise trains, it is common to see cars of the same class in the same type of train. Hence, UP H-70-1's in different coal trains, PFE reefers, S-40-12 stock cars, etc.

If you had ALL of the conductors books for every day for a full
week, now that would be interesting! That would smooth out a lot
of the daily fluctuations. Of course there's seasonal variations,
but that might actually be easy to discern in a large sample.

But the daily fluctuations are the goal...if one wants to model real trains. Again, there were specific trains with specific tasks and, yes, sometimes they were combined. If one wants to simply know what frt cars operated between two points...like between Laramie and Rawlins...over a long period, you would need a large % of the conductor books for that period.

Mike Brock

On the contrary, I think we know a great deal. We know what UP frt trains
looked like. From my conductor's book, we know what 34 trains looked like.

Mike

My point is, can anything useful be inferred from it about the overall
composition of freight trains on the UP mainline? I don't think so. But
as I said before, if you want to model THOSE trains, then it's exactly
what the doctor ordered.

You have a basic assumption that because you see a variety of consists,
you are seeing a cross-section of all the trains on the UP. But how do
you know that? Maybe the same train, different day, had an entirely
different composition because of the ebb and flo of traffic. Was this
conductor high seniority, or extra board? That could make a difference
in what trains he got. Did he get the fast freights, or slow rollers?

Even in my 34 trains, it is easy to see similar trains. For example,
reefer blocks, lumber trains, tank car trains [ both MTY & loaded from
Sinclair ], stock trains, coal trains and even merchandise trains. The
cars will be different but there were specific trains running almost daily...
Roseville Fruit for example.

Mike if you had a month's worth of Roseville Fruit trains, that would be
very interesting. As I said, a whole week's worth of one train (especially
a train like that) can tell you a great deal about THAT train! At least,
about that train in that season. Did you see many Bangor & Aroostook reefers
in your fruit trains? During the summer months BAR reefers were largely out
of work in Maine, but they could be found on the SP being loaded with
California produce. But you would not see that if your data sample was
taken at a different time of year. If you model UP year round, you would
need BAR reefers. But if you model only the fall-winter, you don't.

But the daily fluctuations are the goal...if one wants to model real trains.
Again, there were specific trains with specific tasks and, yes, sometimes
they were combined. If one wants to simply know what frt cars operated
between two points...like between Laramie and Rawlins...over a long period,
you would need a large % of the conductor books for that period.

Well, Mike, it seems we are in agreement! :-)

Tim O'Connor

Tim O'Connor writes:

"Larry, does 2,267 box cars on the UP mainline even represent the traffic of a single typical day? So here we are looking at freight trains spread over four months... or on any given day, less than 1% of the box cars on the main line are sampled."


Yes Tim, I think 2,267 box cars represent three or four days of UP freight traffic across Wyoming in the late 1930s. (Data from 1949 provided by Mark Amfahr show 30 to 33 trains a day between Laramie and Cheyenne.) The information in the three train books covers 120 trains and about 7,000 cars. Ferguson's book is from May 13 to June 21, 40 days, 41 trains, over 2,000 cars, about a 3% sample. Fraley's and Fitz's books span September 12 to October 24, 43 days, 89 trains, nearly 5,000 cars, about a 6.6% sample. Pooling them gives about a 4.5% sample.

I'm not sure that the percentage of the sample matters as much as its size, however. The Gallup Poll routinely uses a sample size of about 1,000 adults when conducting its survey research. If there are 200 million adults in the country, the sample percentage is about 0.0005%. Also, what are the sample sizes and percentages for the data on which the G-N model is based? Does anyone know?

A far more serious potential problem than sample size or percentage is its randomness. Random sampling is generally required for statistically accurate results, and it would be hard to argue that these are random samples. There is nothing we can do about it other than exercise caution when interpreting the results however. And there is no need to over-emphasize this problem either. I think the train books are far preferable to other methods we have of reconstituting the past (photos, videos, ICC reports, etc.).

"What can be learned from this? Nothing, I believe."
I on the other hand learned a lot. So can others if they look at it carefully (and critically). How can one have data from 120 trains and 7,000 cars and learn nothing?!?

"Look at it another way -- suppose you had conductors books for the
same time period from three other conductors. Do you think that the
tallies would be the same? I don't -- not one chance in a thousand.
So then, which would be the representative sample? Answer: neither."

No, they wouldn't be the same, but they are likely to be similar. For example, I would expect them to show the same dominance of UP and SP cars, and I think it is likely that the Central Western ICC region will have more than its fair share of cars, even with UP and SP removed. The New England and Southern regions may have fewer than expected representation also. In any event, that is a question that may have an answer in a few months, because I in fact do have three more conductors' reports from September/October 1938 that I intend to transcribe.

And if it were me I wouldn't worry about which is representative. I would simply pool them.

"If you had ALL of the conductors books for every day for a full week, now that would be interesting!"
Yes, and if a Big Boy were to pull a load of 1950-era cars through Laramie today, that would also be interesting too! :) (And how would we know if it is a typical week?)

Best wishes,
Larry Ostresh
Laramie, Wyoming

Larry Ostresh wrote

I think 2,267 box cars represent three or four days of UP freight traffic across
Wyoming in the late 1930s. (Data from 1949 provided by Mark Amfahr show 30 to 33
trains a day between Laramie and Cheyenne.)

I'm sure I don't need to point out 1949 was a very different year
than 1938, in which the US economy was still deep in recession. I
think someone else already pointed that out, as did Tim Gilbert so
that's all to say about that.

I take your point about 1938 trains per se, but I don't understand
the basis of your statement "[other conductor books] wouldn't be the
same, but they are likely to be similar". The tricky word of course
being "similar"...

I look forward to your compilation of the new books, both separately
(by themselves) and then combined with the other books to see what
happens to the statistics.

Tim O'Connor

Tim O'Connor wrote

Larry Ostresh wrote

I think 2,267 box cars represent three or four days of UP freight traffic across
Wyoming in the late 1930s. (Data from 1949 provided by Mark Amfahr show 30 to 33
trains a day between Laramie and Cheyenne.)

I'm sure I don't need to point out 1949 was a very different year
than 1938, in which the US economy was still deep in recession.

Yes, of course. I would expect therefore that there would have been fewer trains per day in 1938 than in 1949, which would raise my percentages. If you have data showing that the Great Depression led to more trains across Wyoming, I would like to see it. Or if you have better data than Mark provided, please make that public.

I don't understand
the basis of your statement "[other conductor books] wouldn't be the
same, but they are likely to be similar". The tricky word of course
being "similar"...

I think the sentences following the one you quoted spell out precisely what I mean by "similar". I wrote: "For example, I would expect them to show the same dominance of UP and SP cars, and I think it is likely that the Central Western ICC region will have more than its fair share of cars, even with UP and SP removed. The New England and Southern regions may have fewer than expected representation also."

Best wishes,
Larry Ostresh
Laramie, Wyoming

I'm sure I don't need to point out 1949 was a very different year
than 1938, in which the US economy was still deep in recession.

Yes, of course. I would expect therefore that there would have been fewer trains per day in 1938 than in 1949, which would raise my percentages. If you have data showing that the Great Depression led to more trains across Wyoming, I would like to see it. Or if you have better data than Mark provided, please make that public.

It has nothing to do with the number of trains Larry. Tim Gilbert
pointed out that the percentage of home road cars staying on-line
greatly increased throughout the depression years, and so the
distribution of cars nationwide was quite different in 1949 than
in 1938. The more-or-less uniform distribution of plain box cars
is far more apparent in the late 1940's than in the late 1930's.
The year 1938 was a severe recession. Industrial output declined
sharply. I assume that means there were a lot fewer PRR and other
eastern cars on the SP and UP than would be in normal economic
times.

You say your data show "dominance" of SP cars -- but isn't it just
201 or so SP cars in 34 random trains over a period of a month? Now,
that might show "dominance" but it might just also be random luck.
If the UP ran 3 trains a day, I'd say that was a great sample. But
even if UP only ran 20 trains a day... Well, it's not much to go on.

Tim O'

Hi Tim

You said "It has nothing to do with the number of trains Larry".

My comment about fewer trains raising my percentages was in the context of increasing my sample percentages. Mark Amfahr's data showed that 30 – 33 freight trains per day crossed Sherman Hill in 1949. This implied that the 120 trains in my data represented a sample of about 4.5%, not the "less than 1%" that you had previously asserted. If there were fewer than 30-33 trains per day, then my sample percentages would rise. For example if there were only 20 trains per day my sample percentage would be 7% instead of 4.5%. The sample percentage has everything to do with the number of trains – it is the denominator for calculating the percentage.

And then you said:
"Tim Gilbert pointed out that the percentage of home road cars staying on-line greatly increased throughout the depression years, and so the distribution of cars nationwide was quite different in 1949 than in 1938. The more-or-less uniform distribution of plain box cars is far more apparent in the late 1940's than in the late 1930's. The year 1938 was a severe recession. Industrial output declined sharply. I assume that means there were a lot fewer PRR and other eastern cars on the SP and UP than would be in normal economic times."

Agreed!!! That is exactly what I said in post #89909:
"I think I recall Tim Gilbert writing that the G-N hypothesis fits the data well during economic prosperity but does less well during recessions and depressions. The year 1938 was during the Great Depression, of course. The high proportion of home cars (41%) is another indication that companies may be keeping their cars close by. It might be that modelers wishing to have a realistic mix of cars on their trains should pick an era first – or perhaps even a specific year and season, and then check what was happening in the national economy at that time. The choice of the G-N vs. a regional (or any other) model for an accurate freight car composition may well depend on such ephemera."

Best wishes,
Larry Ostresh
Laramie, Wyoming

Tim O'Connor said

"You say your data show "dominance" of SP cars -- but isn't it just 201 or so SP cars in 34 random trains over a period of a month? Now, that might show "dominance" but it might just also be random luck. If the UP ran 3 trains a day, I'd say that was a great sample. But even if UP only ran 20 trains a day... Well, it's not much to go on."

The 201 SP cars represent 15.4% of all non-UP boxcars, whereas according to the G-N hypothesis it should be 3.3%. The expected number of cars is 44 according to G-N. That sounds like SP dominance to me, but of course it could be due to "random luck". That would make the many discussions on this list of the presumed anomaly pointless. Perhaps someone more statistically gifted than I am can tell us how likely the dominance is due to the luck of the draw.

The train books cover 120 trains, not 34. (A large number of the trains are Roseville Fruits and other trains with few or no box cars, as Mike Brock has pointed out in the past couple of days.) I wish I could believe they were "random trains" – that would give me much greater confidence that my results are valid and not some sampling fluke.

Best wishes,
Larry Ostresh
Laramie, Wyoming

Tim O'Connor, commenting on the 1938 data [ I think ] notes:

You say your data show "dominance" of SP cars -- but isn't it just
201 or so SP cars in 34 random trains over a period of a month? Now,
that might show "dominance" but it might just also be random luck.
If the UP ran 3 trains a day, I'd say that was a great sample. But
even if UP only ran 20 trains a day... Well, it's not much to go on.

But, Tim, all of the 1938, 1949, 1951, and 1956 books show SP box cars on the UP to be present MUCH more than projected by G-N.

Mike Brock

Larry Ostrech writes:

"Mark Amfahr's data showed that 30 - 33 freight trains per day crossed Sherman Hill in 1949."

Actually, so that members aren't confused, there is only one known frt conductor book covering Laramie-Rawlins in 1949...the one I have. I gave a copy to Mark. And, actually, it's 34 trains. Interesting trains...at that.

"This implied that the 120 trains in my data represented a sample of about 4.5%, not the "less than 1%" that you had previously asserted. If there were fewer than 30-33 trains per day, then my sample percentages would rise. For example if there were only 20 trains per day my sample percentage would be 7% instead of 4.5%. The sample percentage has everything to do with the number of trains - it is the denominator for calculating the percentage.

And then you said:
"Tim Gilbert pointed out that the percentage of home road cars staying on-line greatly increased throughout the depression years, and so the distribution of cars nationwide was quite different in 1949 than in 1938. The more-or-less uniform distribution of plain box cars is far more apparent in the late 1940's than in the late 1930's."

I'm not clear on this. Where does this come from?

"The year 1938 was a severe recession. Industrial output declined sharply. I assume that means there were a lot fewer PRR and other eastern cars on the SP and UP than would be in normal economic times."

"It might be that modelers wishing to have a realistic mix of cars on their trains should pick an era first - or perhaps even a specific year and season, and then check what was happening in the national economy at that time."

Alas. It's those &%*$# 4-12-2's, 2-8-8-0's and turbines. They all existed in 1954...a VERY good yeeeeaaarr.

Mike Brock

Larry

Ok, you have 120 trains, 7000 cars, 2400 box cars right? Or 20 box
cars per train (on average)?

Here's a simple, straightforward probability calculation --

Let's say 4 out of 100 box cars is owned by SP or T&NO. (I checked my 1940
ORER, the two combined owned 27,740 box, automobile & furniture cars.)

So what is the random chance of a 20 box car freight train with ZERO
SP/TNO box cars?

It's just .96**20 or .44 -- a 44% random chance. Or in other words, with the
SP/TNO owning 4% of the fleet, a 20 box car train has a 56% chance that it will
have -at least one- SP/TNO box car. (It could have 2 or more of course.)

The statistic that we have been discussing is "expectation" -- what is the
"expected" (or average number) of SP box cars. G-N says it is 0.8 (.04*20),
but in your data set of 120 trains it is 1.6 (200/120). Now recall that
probability of at least 1 car -- 56%. The population -difference- between the
observed and expected number in your sample (of 4.5% of freight trains) is
less than 1 car per train. This is why I said it -could- be explained by
random chance, especially since the data set is so small. We both agree
that the recession of 1938 also could skew the data.

Yes, it is highly frustrating to us because we have so little data. We can
certainly learn a lot from conductor's reports -- about cargos, destinations,
composition of individual freight trains, all kinds of operational stuff that
is wonderful to know. I have an SP conductor's book, and it's great. But I'm
just not so comfortable with trying to extrapolate a lot about distribution
of box cars in the USA from a small number of these books. I know Dave and
Tim Gilbert used a lot of other sources.

Tim O'Connor

Mike

Ok, you're wearing me down :-) I dismiss the 1938 books as irrelevant,
but if you show a consistency from 1949-1956 then I think it's worth
some digging down and trying to find out WHY SP box cars were so much
more common on the UP than random distribution would predict. First I
would seek to know what percent of the SP cars were loaded, and what
percents loaded EB/WB. Answers to those might lead further inquiries
in a useful direction...

Tim O'Connor

--- In STMFC@..., Tim O'Connor <timboconnor@...> wrote:

Mike

Ok, you're wearing me down :-) I dismiss the 1938 books as irrelevant,
but if you show a consistency from 1949-1956 then I think it's worth
some digging down and trying to find out WHY SP box cars were so much
more common on the UP than random distribution would predict. First I
would seek to know what percent of the SP cars were loaded, and what
percents loaded EB/WB. Answers to those might lead further inquiries
in a useful direction...

Tim O'Connor

But, Tim, all of the 1938, 1949, 1951, and 1956 books show SP box cars on
the UP to be present MUCH more than projected by G-N.

Mike Brock

Tim, why don't you just look at the 1951 book yourself and tell us what you find? Scanned pages and an Excel transcription are online at www.laramiedepot.org

Why are the 1938 books irrelevant?

Larry Ostresh
Laramie, Wyoming

--- In STMFC@..., "Mike Brock" <brockm@...> wrote:

Larry Ostrech writes:

"Mark Amfahr's data showed that 30 - 33 freight trains per day crossed
Sherman Hill in 1949."

Actually, so that members aren't confused, there is only one known frt
conductor book covering Laramie-Rawlins in 1949...the one I have. I gave a
copy to Mark. And, actually, it's 34 trains. Interesting trains...at that.

Mike, the data Mark gave me is not a conductor book. It is a listing of the passenger and freight trains that passed Sherman on June 4 and 5, 1949. Their were 16 EB and 15 WB on the 4th, 17 EB and 15 WB on the 5th.

Larry Ostresh
Laramie, Wyoming

--- In STMFC@..., "Mike Brock" <brockm@...> wrote:

Larry Ostrech writes:

"Tim Gilbert pointed out that the percentage of home road cars staying
on-line greatly increased throughout the depression years, and so the
distribution of cars nationwide was quite different in 1949 than in 1938.
The more-or-less uniform distribution of plain box cars is far more apparent
in the late 1940's than in the late 1930's."

I'm not clear on this. Where does this come from?

Mike, Tim O'connor wrote this, not me. You'll have to ask him where it comes from.

Larry Ostresh
Laramie, Wyoming

Tim O'Conner writes: I think it's worth some digging down and trying to find out WHY SP box cars were so much more common on the
UP than random distribution would predict.

Uhh, Tim have you looked at a map? The SP coming out of Central California did not have to many interchange partners on the east
end. Far different then what one finds east of the Mississippi. Fewer interchange partners are going to skew the results in my
opinion. What I find interesting in all this is no discussion of UP boxcars on the SP. Did this not happen?

Doug Harding
www.iowacentralrr.org

--- In STMFC@..., Tim O'Connor <timboconnor@...> wrote:

Larry

Ok, you have 120 trains, 7000 cars, 2400 box cars right? Or 20 box
cars per train (on average)?

Here's a simple, straightforward probability calculation --

Let's say 4 out of 100 box cars is owned by SP or T&NO. (I checked my 1940
ORER, the two combined owned 27,740 box, automobile & furniture cars.)

So what is the random chance of a 20 box car freight train with ZERO
SP/TNO box cars?

It's just .96**20 or .44 -- a 44% random chance. Or in other words, with the
SP/TNO owning 4% of the fleet, a 20 box car train has a 56% chance that it will
have -at least one- SP/TNO box car. (It could have 2 or more of course.)

The statistic that we have been discussing is "expectation" -- what is the
"expected" (or average number) of SP box cars. G-N says it is 0.8 (.04*20),
but in your data set of 120 trains it is 1.6 (200/120). Now recall that
probability of at least 1 car -- 56%. The population -difference- between the
observed and expected number in your sample (of 4.5% of freight trains) is
less than 1 car per train. This is why I said it -could- be explained by
random chance, especially since the data set is so small. We both agree
that the recession of 1938 also could skew the data.

Yes, it is highly frustrating to us because we have so little data. We can
certainly learn a lot from conductor's reports -- about cargos, destinations,
composition of individual freight trains, all kinds of operational stuff that
is wonderful to know. I have an SP conductor's book, and it's great. But I'm
just not so comfortable with trying to extrapolate a lot about distribution
of box cars in the USA from a small number of these books. I know Dave and
Tim Gilbert used a lot of other sources.

Tim O'Connor

Hi Tim

The actual percentage of SP cars from the ORER in 1938 is 3.3%, not the 4% you assume. There are 1,308 non-UP box cars, which I believe is the relevant number, not your 2,400. This gives an average number of non-UP box cars per train of about 11, not 20. Based on G-N the expected number of SP cars in the train books is 44, versus the 201 actually found. Thus each of the 120 trains would have to have at least one additional car.

Getting that extra car in each train isn't as easy as it seems. If the process is random, as you hypothesize, 83 of the trains won't have any SP car at all; 31 will have one SP car, 5 or 6 will have two, 1 will have 3. Having more than 3 is too remote to consider. (We can discuss how I obtained these numbers off list if you want – I expect it is of little interest to the group.)

The easiest way to get an extra car (i.e., the way with the greatest likelihood of success) is to add one to each of the 83 trains with no car at all because it is analogous to winning a bet in which the odds are only 83 to 31 against you. Other conversions give you worse odds. Of course winning each and every time for 83 times in succession is highly unlikely – it would be far easier to come up with heads every time in 83 coin tosses – but even if you were to do so you would only have 83 more cars, for a total of 127 SP box cars. You would still need another 74. It can't be done in a million years.

Best wishes,
Larry Ostresh
Laramie, Wyoming