Summary: Transportation And Spatial Modelling
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Basic Concepts
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What assumption does the MNL hold in terms of different alternatives?
That all different alternatives should be i.i.a > independence of irrelevant alternatives.
If red/blue bus problem > Nested logit is more suitable. 
What does an alternative specific constant represent? (ASC)
ASC represents a preference or reluctance (/+) for that alternative. It captures attributes that are not included in the systematic utility function.
It works on differences between alternatives. 
What does a nest parameter of 1 implies?
A nest parameter that equals 1 states that there's NO NEST and that the alternatives within the nest should be considered as independent alternatives. 
How do you adapt a unimodal doubly constrained gravity model when expanding from 3stage to a 4stage model by introducing a logitmodel based mode choice model
 input gravity model is skim of the network
 3 stage the skim is the skim of the car network
 multimodal case it should be a kind of aggregated skim of both modes
 since a logit mode choice is modelled the logsum of the mode choice model could be used as a measure of the aggregated skim. Of course the parameters of the detterence function needs to be adapted as well. 
Supply modeling
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What to do in a system optimal solutions when coming from DUE?
Replace travel time function with marginal cost function 
What does that duality gap aim for?
Minimization of the differences between the a priori matrix and the estimated matrix. This objective thus minimises the sum of the square of the differences at ODlevel. 
Overall Summary
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What are one disadvantage and one advantage of probit assignment?
 Advantage: probit assignment accounts for overlap of routes
 Disadvantage: takes up a lot of computing time than logit 
Describe how the elasticity Ek and it value range could be interpreted (of multiplier)
Ek is the reliability of the count: i.e. value range between 0 and 1. 1 being a fully reliable counts and 0 being a non reliable count.
Multiplier = to achieve a better match between flows and traffic counts 
Describe algorithm steps if there's only one count per OD pair
 Assign the a priori ODmatrix
 Per count:
2a Determine the multipliers per count
2b Multiply the ODpairs passing the count with the corresponding
multiplier
 Assign the a priori ODmatrix

Algorithm with weighted averages of multipliers at OD levels
 Assign the a priori ODmatrix
 Determine the multiplier for each count
 For each ODpair
3a Determine the weighted average of the multipliers
3b Multiply the trips for this ODpair with this weighted average  Assign the updated ODmatrix and go to step 2
 Assign the a priori ODmatrix
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