Thank you so much Robert. Please find the information below.
The scale 1-10 are subjective physical condition ratings scored by inspection
engineers at the site. 1-5 are in very bad conditions (bridge close down to
seriously deteriorated). The rest from 6-10 are categorized as good
condition.However, the proportion of samples in my data are as follows. Bridges
with 1-5 scale covers about 2-3% of total population. The majority of the
bridges are in 7-8. Certainly, I have enough data for model estimation but the
mix of the proportion is good. I attached the detail of condition rating scale
at the end of this message.
As a result, my ordered probit model yield cutting points that cannot capture
level 1-5 well. Even in my in-sample population, the model cannot capture level
2-5 at all. In other words, with the estimated cutting points for level 1-5, I
have zero bridges that belong to level 2-5. Unfortunately, my objective is
especially to analyze statistically what kind of design attributes lead to such
a bad condition. So I would like my model to be able to capture bad condition
bridges as much as it could.
9 EXCELLENT CONDITION
8 VERY GOOD CONDITION - no problems noted.
7 GOOD CONDITION - some minor problems.
6 SATISFACTORY CONDITION - structural elements show some minor
deterioration.
5 FAIR CONDITION - all primary structural elements are sound
but may have minor section loss, cracking,
spalling or scour.
4 POOR CONDITION - advanced section loss, deterioration,
spalling or scour.
3 SERIOUS CONDITION - loss of section, deterioration of
primary structural elements. Fatigue cracks
in steel or shear cracks in concrete may be present.
2 CRITICAL CONDITION - advanced deterioration of primary
structural elements. Fatigue cracks in steel
or shear cracks in concrete may be present or scour may
have removed substructure support. Unless
closely monitored it may be necessary to close the bridge
until corrective action is taken.
1 "IMMINANT" FAILURE CONDITION - major deterioration or
section loss present in critical sructural
components or obvious vertical or horizontal movement
affecting structure stability. Bridge is
closed to traffic but corrective action may put it back in
light service.
0 FAILED CONDITION - out of service; beyond corrective action.
----- Original Message -----From: Robert A LaBudde Date: Saturday, June 16,
2007 9:59 amSubject: Re: [R] [Not R question]: Better fit for order probit
modelTo: [email protected]> At 03:17 AM 6/16/2007, adschai wrote:>
>Thank you so much Robert. I haven't thought about the idea of > >clumping
categories together. One of the reason is because > these > >categories are
bridge condition rating scores. They indeed > represent > >different meaning
and serviceability conditions. They vary from > 0-9. > >I have about 300,000
data in which the first 5 labels, i.e. 0-> 4, are > >bad condition bridge and
there are only less than 1000 > instances in > >total. The worst case, is for
example, score 0 (meaning the > bridge > >is not operatable), I have 60
instances. Score 1 I have about 100.> >> >I would appreciate if you could
provide some opinion as to how > you > >would make the order probit fits better
in this case? Thank you > so > >much in advance.> > You certainly appear to h!
ave enough data to populate these > categories. Your problems in a getting a
good fit may relate to > other problems.> > You need to supply more information
in order to say more.> > What are the definitions of each category?> > Is the
ordering consistent, or are there really two different > scales, > one for
bridge with essentially no problems, and another for > those > with serious
damage?> > What evidence do you have that your fit is poor?> > What model are
you fitting?> > Etc.> >
================================================================> Robert A.
LaBudde, PhD, PAS, Dpl. ACAFS e-mail: [EMAIL PROTECTED]> Least Cost
Formulations, Ltd. URL: http://lcfltd.com/> 824 Timberlake Drive
Tel: 757-467-0954> Virginia Beach, VA 23464-3239
Fax: 757-467-2947> > "Vere scire est per causas scire"> >
______________________________________________> [email protected]
mailing list> https://stat.ethz.ch/mailman/listinfo/r-help> PLEASE do r!
ead the posting guide http://www.R-> project.org/posting-guide.html> a
nd provide commented, minimal, self-contained, reproducible code.>
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