?===============================================================
? Basic Multinomial Choice Models.
? Data set = mnc.lpj
?===============================================================
? First part based on shoe brand choice
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SAMPLE ; 1 - 12800 $
?
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?  Basic functional form
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 NLOGIT  ; Lhs = choice 
         ; Choices = brand1,brand2,brand3,none
         ; Rhs = fash, qual, price, pricesq,asc4 $

?---------------------------------------------------------------
? Expand the functional form by adding variables.  Add this to
? your model command.
? ******************>>> Based on the LR test, are these three
? ******************>>> variables significant?
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         ; Rh2 = male, age24, age39
?
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? Test for age difference in preferences
? ******************>>> What is the result of the test?
? ******************>>> Repeat the test for gender difference.
? ******************>>> Use MALE instead of YOUNG in the test.
?---------------------------------------------------------------
CREATE  ; young = age25 $
NLOGIT  ; For[(test) young =*,0,1] 
        ; your model specification (must not include age25) $

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? Partial effects
? ******************>>> Interpret the cross brand elasticities.
? ******************>>> Do these elasticities make sense?
?---------------------------------------------------------------
NLOGIT   ; Lhs = Choice ; Choices=Brand1,Brand2,Brand3,None
         ; Rhs = Fash,Qual,Price,Asc4 
         ; Effects : Price (*) ; full$

?---------------------------------------------------------------
? Simulate a general price increase to examine effects.
? The simulator does not know that pricesq = price squared.
? In order to get the simulation right, it is necessary to
? change both price and its square.
?******************>>>  Try increasing the price change to
?******************>>>  40%. How do the choices change
?---------------------------------------------------------------
NLOGIT ; Lhs = Choice ; Choices=Brand1,Brand2,Brand3,None
       ; Rhs = Fash,Qual,Price,Pricesq,Asc4 $
NLOGIT ; Lhs = Choice ; Choices=Brand1,Brand2,Brand3,None
       ; Rhs = Fash,Qual,Price,Pricesq,Asc4 
       ; Simulate = * ; Scenario: price (brand*) = [*] 1.1/
                                  pricesq(brand*)= [*]1.21 $

?---------------------------------------------------------------
? Simulate price increase for one brand to examine effects
?******************>>> Is BRAND2 different from BRAND1?
?---------------------------------------------------------------
CLOGIT ; Lhs = Choice ; Choices=Brand1,Brand2,Brand3,None
       ; Rhs = Fash,Qual,Price,Asc4 
       ; Effects : Price (*) $
CLOGIT ; Lhs = Choice ; Choices=Brand1,Brand2,Brand3,None
       ; Rhs = Fash,Qual,Price,Asc4 
       ; Simulation = * 
       ; Scenario: Price (Brand1)  = [*] 1.5 $ 

?---------------------------------------------------------------
? Testing for IIA
?******************>>>  What is the result of the test?
?---------------------------------------------------------------
SAMPLE ; All $
CLOGIT ; Lhs = Choice ; Choices=Brand1,Brand2,Brand3,None
       ; Rhs = Fash,Qual,Price,Asc4  $
CLOGIT ; Lhs = Choice ; Choices=Brand1,Brand2,Brand3,None
       ; Rhs = Fash,Qual,Price,Asc4 ; IAS = Brand3  $


?---------------------------------------------------------------
?  Do men pay different attention to fashion than women?
?  Is the difference statistically significant?
?  The simulator includes the MALE effect in the FASHion part
?  of the utility function.  The simulation compares the case
?  in which males care differently about fashion to the case in
?  which they don't.  
?******************>>> What is the effect?
?---------------------------------------------------------------
Create ; MaleFash = Male*Fash $
CLOGIT ; Lhs = Choice ; Choices=Brand1,Brand2,Brand3,None
       ; Rhs = Fash,Qual,Price,Asc4,MaleFash $
CLOGIT ; Lhs = Choice ; Choices=Brand1,Brand2,Brand3,None
       ; Rhs = Fash,Qual,Price,Asc4,MaleFash 
       ; Simulation = * ; Scenario: MaleFash(*) = [*] 0 $


?===============================================================
? Basic Multinomial Choice Models.
? Data set = mnc.lpj
?===============================================================
? Second part based on travel mode choice
?---------------------------------------------------------------
SAMPLE ; 1 - 840 $

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? Multinomial Probit Model
?******************>>> Compare the elasticities produced by the
?******************>>> two models
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NLOGIT  ; Lhs = Mode ; output=ic
        ; Choices = Air,Train,Bus,Car
        ; Rhs = TTME,INVC,INVT,GC; Rh2=One,Hinc 
        ; Effects: invc (*) $
NLOGIT  ; Lhs = Mode ; MNP ; PTS = 5 ; Maxit = 5 ; Halton
        ; Choices = Air,Train,Bus,Car
        ; Rhs = TTME,INVC,INVT,GC; Rh2=One,Hinc 
        ; Effects: invc (*) $

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? Nested Logit Model
?******************>>> Try a few different nest structures
?---------------------------------------------------------------
NLOGIT  ; Lhs = Mode ; Choices=Air,Train,Bus,Car
        ; Rhs = One,GC,TTME,INVT,INVC
        ; Tree = Private(Air,Car),Public(Train,Bus)
        ; Show Tree $
CALC    ; LOGLU = LOGL $

?---------------------------------------------------------------
? Constrain IV parameters to produce MNL model
?******************>>>  What is the result of the test of IIA?
?---------------------------------------------------------------
NLOGIT  ; Lhs = Mode ; Choices=Air,Train,Bus,Car
        ; Rhs = One,GC,TTME,INVT,INVC
        ; Tree = Private(Air,Car),Public(Train,Bus)
        ; IVSET:(Private,Public)=[1] $
CALC    ; LOGLR = LOGL $
CALC    ; List ; LRTEST = 2*(LOGLU - LOGLR) $

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?  Degenerate branch.  Two normalizations
?---------------------------------------------------------------
NLOGIT  ; Lhs = Mode ; Choices=Air,Train,Bus,Car
        ; Rhs = One,GC,TTME,INVT,INVC
        ; Tree = Fly(Air),Ground(Car,Train,Bus) $
NLOGIT  ; Lhs = Mode ; Choices=Air,Train,Bus,Car
        ; Rhs = One,GC,TTME,INVT,INVC
        ; Tree = Fly(Air),Ground(Car,Train,Bus) ; RU2 $

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? Use nested logit to reveal scaling.
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NLOGIT  ; Lhs = Mode ; Choices=Air,Train,Bus,Car
        ; Rhs = One,GC,TTME,INVT,INVC
        ; Tree = Fly(Air),Drive(Car),Rail(Train),Ride(Bus) 
        ; IVSET: (Ride) = [1] ; Par $
NLOGIT  ; Lhs = Mode ; Choices=Air,Train,Bus,Car
        ; Rhs = One,GC,TTME,INVT,INVC
        ; HET ; SDV = SA,ST,1.0,SC $