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Unreasonable VTT value in the segment

Ask questions about the results reported after estimation. If the output includes errors, please include your model code if possible.
Post Reply
peggyli
Posts: 1
Joined: 02 May 2023, 14:06

Unreasonable VTT value in the segment

Post by peggyli »

Dear Stephane,

I am doing model estimation on travel-related SP data and have encountered some unexpected results.

Specifically, I have two types of choice experiments in my SP survey: economy class design and upper class design. The designs, attributes, and levels are the same for both classes, except for a 60% increase in the cost attribute for the upper class design. Respondents are assigned to one of the two designs based on their answers to previous questions before participating in the choice experiment.

After collecting the data, I found that 58% of the respondents did the upper class design, while the others did the economy class design. I estimated a MNL model using all the data and obtained a value of time of 145.1 (h/currency). When I segmented the data into economy and upper class and estimated separate MNL models. However, I found that the value of time for the economy class segment was 179 (h/currency), which is higher than the pooled data value of time. The value of time for the upper class segment was 797 (h/currency).

I am wondering if it is possible for the value of time for the economy class to be higher than the pooled data value of time. I would have expected the order to be VTT_economyclass < VTT_pooleddata < VTT_upperclass. Could there be something wrong with the design or estimation?

I have attached the code and results for the three MNL models below.
CODE: The code I'm presenting here is for the pooled data. The code for the two segments is identical except for the data subset.

Code: Select all

# ################################################################# #
#### LOAD LIBRARY AND DEFINE CORE SETTINGS                       ####
# ################################################################# #
#install.packages("apollo")
### Clear memory
rm(list = ls())

dirname(rstudioapi::getActiveDocumentContext()$path) #checking path
setwd(dirname(rstudioapi::getActiveDocumentContext()$path))
getwd() #checking active path

### Load Apollo library
library("apollo")

### Initialise code
apollo_initialise()

### Set core controls
apollo_control = list(
  modelName       = "MNL_data_FINAL_nofilter_ASC",
  modelDescr      = "MNL model on main data 6min  no filter WITH ASC",
  indivID         = "ID", 
  outputDirectory = "output"
)

# ################################################################# #
#### LOAD DATA AND APPLY ANY TRANSFORMATIONS                     ####
# ################################################################# #

### Loading data from package
### if data is to be loaded from a file (e.g. called data.csv), 
### the code would be: database = read.csv("data.csv",header=TRUE)
database = read.csv("Processed_FINAL_6min_NOFILTER.csv",header=TRUE)

#####for economy class#####
database<- subset (database, UPP_Block==0)
#####for upper class#####
database<- subset (database, ECO_Block==0)

# ################################################################# #
#### DEFINE MODEL PARAMETERS                                     ####
# ################################################################# #

### Vector of parameters, including any that are kept fixed in estimation
apollo_beta = c(ASC1             = 0,
                ASC2                     = 0,
                ASC3                     = 0,
                b_fare                   = 0, 
                b_time                  = 0, 
                b_type1                 = 0, 
                b_type2                 = 0, 
                b_type3                 = 0,
                b_type0                 = 0,
                b_emission_reduction    = 0)

### Vector with names (in quotes) of parameters to be kept fixed at their starting value in apollo_beta, use apollo_beta_fixed = c() if none
apollo_fixed = c("b_type0","ASC3")

# ################################################################# #
#### GROUP AND VALIDATE INPUTS                                   ####
# ################################################################# #

apollo_inputs = apollo_validateInputs()

# ################################################################# #
#### DEFINE MODEL AND LIKELIHOOD FUNCTION                        ####
# ################################################################# #

apollo_probabilities=function(apollo_beta, apollo_inputs, functionality="estimate"){
  
  ### Function initialisation: do not change the following three commands
  ### Attach inputs and detach after function exit
  apollo_attach(apollo_beta, apollo_inputs)
  on.exit(apollo_detach(apollo_beta, apollo_inputs))
  
  ### Create list of probabilities P
  P = list()
  
  ### List of utilities: these must use the same names as in mnl_settings, order is irrelevant
  V = list()
  V[["alt1"]] = ASC1 + b_fare * alt1.fare + b_time * alt1.time + b_type1 * (alt1.type ==1) + b_type2 * (alt1.type ==2) + b_type3 * (alt1.type ==3)+ b_type0* (alt1.type ==0) + b_emission_reduction * alt1.emission      
  V[["alt2"]] = ASC2 + b_fare * alt2.fare + b_time * alt2.time + b_type1 * (alt2.type ==1) + b_type2 * (alt2.type ==2) + b_type3 * (alt2.type ==3)+ 
 b_type0 * (alt2.type ==0) + b_emission_reduction * alt2.emission  
  V[["alt3"]] = ASC3 + b_fare * alt3.fare + b_time * alt3.time + b_type1 * (alt3.type ==1) + b_type2 * (alt3.type ==2) + b_type3* (alt3.type ==3)+ 
 b_type0* (alt3.type ==0) + b_emission_reduction * alt3.emission 
 
  ### Define settings for MNL model component
  mnl_settings = list(
    alternatives  = c(alt1=1, alt2=2, alt3=3),
    #avail         = list(alt1=1, alt2=1, alt3=1),
    choiceVar     = choice,
    utilities     = V
  )
  
  ### Compute probabilities using MNL model
  P[["model"]] = apollo_mnl(mnl_settings, functionality)
  
  ### Take product across observation for same individual
  P = apollo_panelProd(P, apollo_inputs, functionality)
  
  ### Prepare and return outputs of function
  P = apollo_prepareProb(P, apollo_inputs, functionality)
  return(P)
}

# ################################################################# #
#### MODEL ESTIMATION                                            ####
# ################################################################# #

model = apollo_estimate(apollo_beta, apollo_fixed,
                        apollo_probabilities, apollo_inputs)

# ################################################################# #
#### MODEL OUTPUTS                                               ####
# ################################################################# #

# ----------------------------------------------------------------- #
#---- FORMATTED OUTPUT (TO SCREEN)                               ----
# ----------------------------------------------------------------- #

apollo_modelOutput(model)

# ----------------------------------------------------------------- #
#---- FORMATTED OUTPUT (TO FILE, using model name)               ----
# ----------------------------------------------------------------- #

apollo_saveOutput(model)

# ----------------------------------------------------------------- #
#---- FUNCTIONS OF MODEL PARAMETERS                              ----
# ----------------------------------------------------------------- #

#deltaMethod_settings=list(operation="ratio", parName1="b_time", parName2="b_fare", multPar1 = 60)
#apollo_deltaMethod(model, deltaMethod_settings)

apollo_deltaMethod(model,deltaMethod_settings = list(operation="ratio",
                                                     parName1="b_time",
                                                     parName2="b_fare",
                                                     multPar1=60))

Results for the pooled data:

Code: Select all


Model name                                  : MNL_data_FINAL_nofilter_ASC
Model description                           : MNL model on main data 6min  no filter WITH ASC
Model run at                                : 2023-05-03 14:59:35
Estimation method                           : bfgs
Model diagnosis                             : successful convergence 
Number of individuals                       : 3188
Number of rows in database                  : 28692
Number of modelled outcomes                 : 28692

Number of cores used                        :  1 
Model without mixing

LL(start)                                   : -31521.38
LL at equal shares, LL(0)                   : -31521.38
LL at observed shares, LL(C)                : -30988.81
LL(final)                                   : -27690.19
Rho-squared vs equal shares                  :  0.1215 
Adj.Rho-squared vs equal shares              :  0.1213 
Rho-squared vs observed shares               :  0.1064 
Adj.Rho-squared vs observed shares           :  0.1062 
AIC                                         :  55396.37 
BIC                                         :  55462.49 

Estimated parameters                        :  8
Time taken (hh:mm:ss)                       :  00:00:7.76 
     pre-estimation                         :  00:00:2.26 
     estimation                             :  00:00:2.55 
     post-estimation                        :  00:00:2.96 
Iterations                                  :  16  
Min abs eigenvalue of Hessian               :  170.649 

Unconstrained optimisation.

These outputs have had the scaling used in estimation applied to them.
Estimates:
                        Estimate        s.e.   t.rat.(0)    Rob.s.e. Rob.t.rat.(0)
ASC1                    0.172113     0.01663      10.352     0.01605        10.727
ASC2                    0.138729     0.01665       8.332     0.01639         8.464
ASC3                    0.000000          NA          NA          NA            NA
b_fare                 -0.001340   3.318e-05     -40.389   4.114e-05       -32.574
b_time                 -0.003241  6.6913e-04      -4.844  7.5585e-04        -4.288
b_type1                   0.402288     0.03202      12.565     0.03626        11.094
b_type2                   0.809267     0.05778      14.005     0.06104        13.257
b_type3                 0.575849     0.04962      11.605     0.05525        10.423
b_type0                  0.000000          NA          NA          NA            NA
b_emission_reduction    0.005278  4.3509e-04      12.130  4.6338e-04        11.390


Overview of choices for MNL model component :
                                     alt1     alt2     alt3
Times available                  28692.00 28692.00 28692.00
Times chosen                      9523.00 11833.00  7336.00
Percentage chosen overall           33.19    41.24    25.57
Percentage chosen when available    33.19    41.24    25.57


Classical covariance matrix:
                                     ASC1                 ASC2               b_fare         b_flighttime
ASC1                           2.7645e-04           1.5238e-04            3.246e-08            8.430e-07
ASC2                           1.5238e-04           2.7721e-04            1.983e-08           -7.225e-07
b_fare                          3.246e-08            1.983e-08            1.101e-09            1.437e-08
b_time                    8.430e-07           -7.225e-07            1.437e-08            4.477e-07
b_b_type1                         -2.241e-05           -8.294e-05           -3.323e-07           -1.556e-06
b_b_type2                          -6.950e-05           -6.552e-05           -3.962e-07           -1.318e-05
b_b_type3                           -5.890e-05           -6.721e-05           -4.059e-07           -1.190e-05
b_emission_reduction            1.894e-07           -3.624e-08           -5.789e-10           -8.596e-09
                                    b_SAF                 b_EA                 b_HA b_emission_reduction
ASC1                           -2.241e-05           -6.950e-05           -5.890e-05            1.894e-07
ASC2                           -8.294e-05           -6.552e-05           -6.721e-05           -3.624e-08
b_fare                         -3.323e-07           -3.962e-07           -4.059e-07           -5.789e-10
b_time                   -1.556e-06           -1.318e-05           -1.190e-05           -8.596e-09
b_type1                           0.001025             0.001232             0.001233           -1.053e-05
b_type2                            0.001232             0.003339             0.002290           -1.808e-05
b_type3                            0.001233             0.002290             0.002462           -1.814e-05
b_emission_reduction           -1.053e-05           -1.808e-05           -1.814e-05            1.893e-07

Robust covariance matrix:
                                     ASC1                 ASC2               b_fare         b_flighttime
ASC1                           2.5745e-04           1.4009e-04            8.650e-08            1.965e-06
ASC2                           1.4009e-04           2.6866e-04            8.254e-09           -2.439e-07
b_fare                          8.650e-08            8.254e-09            1.693e-09            1.645e-08
b_time                         1.965e-06           -2.439e-07            1.645e-08            5.713e-07
b_type1                         2.551e-05           -6.169e-05           -2.137e-07           -4.055e-06
b_type2                           -5.694e-05           -5.486e-05           -4.522e-07           -1.611e-05
b_type3                       -1.799e-05           -5.481e-05           -3.423e-07           -1.625e-05
b_emission_reduction           -2.446e-07           -1.341e-07           -1.855e-09           -9.764e-09
                                    b_SAF                 b_EA                 b_HA b_emission_reduction
ASC1                            2.551e-05           -5.694e-05           -1.799e-05           -2.446e-07
ASC2                           -6.169e-05           -5.486e-05           -5.481e-05           -1.341e-07
b_fare                         -2.137e-07           -4.522e-07           -3.423e-07           -1.855e-09
b_time                   -4.055e-06           -1.611e-05           -1.625e-05           -9.764e-09
b_type1                            0.001315             0.001558             0.001614           -1.058e-05
b_type2                             0.001558             0.003726             0.002821           -1.953e-05
b_type3                            0.001614             0.002821             0.003052           -1.950e-05
b_emission_reduction           -1.058e-05           -1.953e-05           -1.950e-05            2.147e-07

Classical correlation matrix:
                                     ASC1                 ASC2               b_fare         b_flighttime
ASC1                              1.00000             0.550432              0.05884              0.07577
ASC2                              0.55043             1.000000              0.03589             -0.06485
b_fare                            0.05884             0.035893              1.00000              0.64741
b_time                      0.07577            -0.064849              0.64741              1.00000
b_type1                           -0.04209            -0.155598             -0.31284             -0.07265
b_type2                            -0.07234            -0.068104             -0.20667             -0.34090
b_type3                           -0.07139            -0.081352             -0.24653             -0.35829
b_emission_reduction              0.02618            -0.005002             -0.04010             -0.02953
                                    b_SAF                 b_EA                 b_HA b_emission_reduction
ASC1                             -0.04209             -0.07234             -0.07139             0.026178
ASC2                             -0.15560             -0.06810             -0.08135            -0.005002
b_fare                           -0.31284             -0.20667             -0.24653            -0.040099
b_time                     -0.07265             -0.34090             -0.35829            -0.029526
b_type1                            1.00000              0.66586              0.77612            -0.756082
b_type2                           0.66586              1.00000              0.79856            -0.719240
b_type3                           0.77612              0.79856              1.00000            -0.840282
b_emission_reduction             -0.75608             -0.71924             -0.84028             1.000000

Robust correlation matrix:
                                     ASC1                 ASC2               b_fare         b_flighttime
ASC1                              1.00000              0.53265              0.13104              0.16202
ASC2                              0.53265              1.00000              0.01224             -0.01969
b_fare                            0.13104              0.01224              1.00000              0.52884
b_time                           0.16202             -0.01969              0.52884              1.00000
b_type1                           0.04384             -0.10379             -0.14322             -0.14794
b_type2                           -0.05813             -0.05483             -0.18005             -0.34906
b_type3                             -0.02029             -0.06052             -0.15058             -0.38906
b_emission_reduction             -0.03290             -0.01765             -0.09731             -0.02788
                                    b_SAF                 b_EA                 b_HA b_emission_reduction
ASC1                              0.04384             -0.05813             -0.02029             -0.03290
ASC2                             -0.10379             -0.05483             -0.06052             -0.01765
b_fare                           -0.14322             -0.18005             -0.15058             -0.09731
b_time                     -0.14794             -0.34906             -0.38906             -0.02788
b_type1                          1.00000              0.70379              0.80568             -0.62984
b_type2                           0.70379              1.00000              0.83637             -0.69058
b_type3                              0.80568              0.83637              1.00000             -0.76155
b_emission_reduction             -0.62984             -0.69058             -0.76155              1.00000

 20 worst outliers in terms of lowest average per choice prediction:
   ID Avg prob per choice
 1378           0.1568203
  875           0.1654853
   61           0.1669630
 2142           0.1682588
 2075           0.1696047
  156           0.1728958
  248           0.1728958
  255           0.1728958
 2512           0.1739157
  134           0.1742798
  225           0.1757682
  173           0.1765429
 1893           0.1774203
 2117           0.1805586
 2128           0.1812739
 2988           0.1828989
 1087           0.1841452
  911           0.1859834
 2476           0.1868619
  885           0.1883451

Changes in parameter estimates from starting values:
                         Initial    Estimate  Difference
ASC1                       0.000    0.172113    0.172113
ASC2                       0.000    0.138729    0.138729
ASC3                       0.000    0.000000    0.000000
b_fare                     0.000   -0.001340   -0.001340
b_time               0.000   -0.003241   -0.003241
b_type1                     0.000    0.402288    0.402288
b_type2                      0.000    0.809267    0.809267
b_type3                    0.000    0.575849    0.575849
b_type0                       0.000    0.000000    0.000000
b_emission_reduction       0.000    0.005278    0.005278

Settings and functions used in model definition:

apollo_control
--------------
                       Value                                            
modelName              "MNL_data_FINAL_nofilter_ASC"               
modelDescr             "MNL model on main data 6min  no filter WITH ASC"
indivID                "ID"                                             
outputDirectory        "output/"                                        
debug                  "FALSE"                                          
nCores                 "1"                                              
workInLogs             "FALSE"                                          
seed                   "13"                                             
mixing                 "FALSE"                                          
HB                     "FALSE"                                          
noValidation           "FALSE"                                          
noDiagnostics          "FALSE"                                          
calculateLLC           "TRUE"                                           
panelData              "TRUE"                                           
analyticGrad           "TRUE"                                           
analyticGrad_manualSet "FALSE"                                          

Hessian routines attempted
--------------
numerical jacobian of LL analytical gradient

Scaling in estimation
--------------
                           Value
ASC1                 0.172113166
ASC2                 0.138729148
b_fare               0.001340111
b_time         0.003240962
b_type1                0.402283217
b_type2            0.809269652
b_type3             0.575853885
b_emission_reduction 0.005277718

Scaling used in computing Hessian
--------------
                           Value
ASC1                 0.172113275
ASC2                 0.138729435
b_fare               0.001340110
b_time         0.003240961
b_type1                0.402287777
b_type2            0.809266541
b_type3             0.575848824
b_emission_reduction 0.005277772


Running Delta method computations
                                                      Value Robust s.e. Rob t-ratio (0)
Ratio of b_time (multiplied by 60) and b_fare:  145.1       31.71           4.576

Results for Economy class

Code: Select all

Model name                                  : MNL_data_6min_ECO_ASC
Model description                           : MNL model on main data 6min  no filter WITH ASC ECONOMY CLASS
Model run at                                : 2023-05-03 15:47:30
Estimation method                           : bfgs
Model diagnosis                             : successful convergence 
Number of individuals                       : 1325
Number of rows in database                  : 11925
Number of modelled outcomes                 : 11925

Number of cores used                        :  1 
Model without mixing

LL(start)                                   : -13100.95
LL at equal shares, LL(0)                   : -13100.95
LL at observed shares, LL(C)                : -12949.48
LL(final)                                   : -9866.76
Rho-squared vs equal shares                  :  0.2469 
Adj.Rho-squared vs equal shares              :  0.2463 
Rho-squared vs observed shares               :  0.2381 
Adj.Rho-squared vs observed shares           :  0.2374 
AIC                                         :  19749.52 
BIC                                         :  19808.61 

Estimated parameters                        :  8
Time taken (hh:mm:ss)                       :  00:00:7.37 
     pre-estimation                         :  00:00:1.78 
     estimation                             :  00:00:2.18 
     post-estimation                        :  00:00:3.41 
Iterations                                  :  20  
Min abs eigenvalue of Hessian               :  57.03027 

Unconstrained optimisation.

These outputs have had the scaling used in estimation applied to them.
Estimates:
                        Estimate        s.e.   t.rat.(0)    Rob.s.e. Rob.t.rat.(0)
ASC1                    0.050441    0.029074       1.735    0.027721         1.820
ASC2                    0.177005    0.027309       6.482    0.026521         6.674
ASC3                    0.000000          NA          NA          NA            NA
b_fare                 -0.004243   8.993e-05     -47.175  1.1908e-04       -35.627
b_time           -0.012658    0.001069     -11.844    0.001091       -11.606
b_type1                   0.211077    0.056914       3.709    0.062077         3.400
b_type2                    0.874358    0.098243       8.900    0.094061         9.296
b_type3                    0.416190    0.087601       4.751    0.087694         4.746
b_type0                    0.000000          NA          NA          NA            NA
b_emission_reduction    0.008422  7.5953e-04      11.089  7.7564e-04        10.858


Overview of choices for MNL model component :
                                     alt1     alt2     alt3
Times available                  11925.00 11925.00 11925.00
Times chosen                      3409.00  4874.00  3642.00
Percentage chosen overall           28.59    40.87    30.54
Percentage chosen when available    28.59    40.87    30.54


Classical covariance matrix:
                                     ASC1                 ASC2               b_fare         b_flighttime                b_SAF
ASC1                           8.4530e-04           2.8867e-04            8.612e-08            6.410e-06           2.0328e-04
ASC2                           2.8867e-04           7.4579e-04            7.665e-08           -1.548e-06          -2.6109e-04
b_fare                          8.612e-08            7.665e-08            8.088e-09            6.118e-08           -1.638e-06
b_time                    6.410e-06           -1.548e-06            6.118e-08            1.142e-06           -4.718e-06
b_type1                           2.0328e-04          -2.6109e-04           -1.638e-06           -4.718e-06             0.003239
b_type2                             6.102e-05          -2.2868e-04           -1.252e-06           -3.026e-05             0.003750
b_type3                          -1.8371e-04          -2.8726e-04           -1.717e-06           -3.205e-05             0.003781
b_emission_reduction            1.191e-06            5.585e-07           -6.302e-09           -1.465e-08           -3.108e-05
                                     b_EA                 b_HA b_emission_reduction
ASC1                            6.102e-05          -1.8371e-04            1.191e-06
ASC2                          -2.2868e-04          -2.8726e-04            5.585e-07
b_fare                         -1.252e-06           -1.717e-06           -6.302e-09
b_time                   -3.026e-05           -3.205e-05           -1.465e-08
b_type1                            0.003750             0.003781           -3.108e-05
b_type2                              0.009652             0.006813           -5.506e-05
b_type3                             0.006813             0.007674           -5.632e-05
b_emission_reduction           -5.506e-05           -5.632e-05            5.769e-07

Robust covariance matrix:
                                     ASC1                 ASC2               b_fare         b_flighttime                b_SAF
ASC1                           7.6843e-04           2.7410e-04            4.031e-07            1.018e-05            7.003e-05
ASC2                           2.7410e-04           7.0336e-04            1.158e-07            4.000e-07          -2.5901e-04
b_fare                          4.031e-07            1.158e-07            1.418e-08            6.574e-08           -1.374e-06
b_time                    1.018e-05            4.000e-07            6.574e-08            1.189e-06           -6.493e-06
b_type1                            7.003e-05          -2.5901e-04           -1.374e-06           -6.493e-06             0.003854
b_type2                          -2.3689e-04          -2.8245e-04           -1.276e-06           -2.896e-05             0.004000
b_type3                      -4.4810e-04          -3.4229e-04           -1.517e-06           -3.172e-05             0.004127
b_emission_reduction            2.538e-06            9.365e-07           -1.240e-08           -1.334e-08           -2.831e-05
                                     b_EA                 b_HA b_emission_reduction
ASC1                          -2.3689e-04          -4.4810e-04            2.538e-06
ASC2                          -2.8245e-04          -3.4229e-04            9.365e-07
b_fare                         -1.276e-06           -1.517e-06           -1.240e-08
b_time                   -2.896e-05           -3.172e-05           -1.334e-08
b_type1                             0.004000             0.004127           -2.831e-05
b_type2                            0.008847             0.006580           -4.741e-05
b_type3                         0.006580             0.007690           -5.231e-05
b_emission_reduction           -4.741e-05           -5.231e-05            6.016e-07

Classical correlation matrix:
                                     ASC1                 ASC2               b_fare         b_flighttime                b_SAF
ASC1                              1.00000              0.36357              0.03294              0.20631              0.12285
ASC2                              0.36357              1.00000              0.03121             -0.05303             -0.16798
b_fare                            0.03294              0.03121              1.00000              0.63658             -0.32006
b_time                      0.20631             -0.05303              0.63658              1.00000             -0.07757
b_type1                              0.12285             -0.16798             -0.32006             -0.07757              1.00000
b_type2                         0.02136             -0.08523             -0.14168             -0.28819              0.67071
b_type3                         -0.07213             -0.12008             -0.21800             -0.34230              0.75843
b_emission_reduction              0.05394              0.02693             -0.09226             -0.01805             -0.71897
                                     b_EA                 b_HA b_emission_reduction
ASC1                              0.02136             -0.07213              0.05394
ASC2                             -0.08523             -0.12008              0.02693
b_fare                           -0.14168             -0.21800             -0.09226
b_time                     -0.28819             -0.34230             -0.01805
b_type1                              0.67071              0.75843             -0.71897
b_type2                             1.00000              0.79167             -0.73787
b_type3                          0.79167              1.00000             -0.84650
b_emission_reduction             -0.73787             -0.84650              1.00000

Robust correlation matrix:
                                     ASC1                 ASC2               b_fare         b_flighttime                b_SAF
ASC1                              1.00000              0.37283              0.12212              0.33666              0.04070
ASC2                              0.37283              1.00000              0.03666              0.01383             -0.15732
b_fare                            0.12212              0.03666              1.00000              0.50620             -0.18592
b_time                      0.33666              0.01383              0.50620              1.00000             -0.09591
b_type1                              0.04070             -0.15732             -0.18592             -0.09591              1.00000
b_type2                            -0.09085             -0.11322             -0.11392             -0.28229              0.68508
b_type3                         -0.18433             -0.14717             -0.14527             -0.33161              0.75815
b_emission_reduction              0.11805              0.04553             -0.13429             -0.01577             -0.58788
                                     b_EA                 b_HA b_emission_reduction
ASC1                             -0.09085              -0.1843              0.11805
ASC2                             -0.11322              -0.1472              0.04553
b_fare                           -0.11392              -0.1453             -0.13429
b_time                     -0.28229              -0.3316             -0.01577
b_type1                              0.68508               0.7582             -0.58788
b_type2                        1.00000               0.7977             -0.64990
b_type3                          0.79766               1.0000             -0.76912
b_emission_reduction             -0.64990              -0.7691              1.00000

 20 worst outliers in terms of lowest average per choice prediction:
   ID Avg prob per choice
  173           0.1085297
 2619           0.1167428
  906           0.1273156
 1684           0.1298964
  106           0.1415237
 1241           0.1430520
 1221           0.1464643
  315           0.1524352
 2530           0.1588139
 1208           0.1594307
 2179           0.1606433
 1964           0.1633451
 2324           0.1654127
   53           0.1658439
  126           0.1660460
 2666           0.1667559
  844           0.1669666
  798           0.1724656
 1029           0.1728904
 3052           0.1736867

Changes in parameter estimates from starting values:
                         Initial    Estimate  Difference
ASC1                       0.000    0.050441    0.050441
ASC2                       0.000    0.177005    0.177005
ASC3                       0.000    0.000000    0.000000
b_fare                     0.000   -0.004243   -0.004243
b_time               0.000   -0.012658   -0.012658
b_type1                       0.000    0.211077    0.211077
b_type2                      0.000    0.874358    0.874358
b_type3                   0.000    0.416190    0.416190
b_type0                   0.000    0.000000    0.000000
b_emission_reduction       0.000    0.008422    0.008422

Settings and functions used in model definition:

apollo_control
--------------
                       Value                                                          
modelName              "MNL_data_6min_ECO_ASC"                                        
modelDescr             "MNL model on main data 6min  no filter WITH ASC ECONOMY CLASS"
indivID                "ID"                                                           
outputDirectory        "output/"                                                      
debug                  "FALSE"                                                        
nCores                 "1"                                                            
workInLogs             "FALSE"                                                        
seed                   "13"                                                           
mixing                 "FALSE"                                                        
HB                     "FALSE"                                                        
noValidation           "FALSE"                                                        
noDiagnostics          "FALSE"                                                        
calculateLLC           "TRUE"                                                         
panelData              "TRUE"                                                         
analyticGrad           "TRUE"                                                         
analyticGrad_manualSet "FALSE"                                                        

Hessian routines attempted
--------------
numerical jacobian of LL analytical gradient

Scaling in estimation
--------------
                           Value
ASC1                 0.050440637
ASC2                 0.177005289
b_fare               0.004242533
b_time         0.012657870
b_type1                 0.211076794
b_type2           0.874359201
b_type3             0.416187921
b_emission_reduction 0.008422139

Scaling used in computing Hessian
--------------
                           Value
ASC1                 0.050440702
ASC2                 0.177004777
b_fare               0.004242531
b_flighttime         0.012657788
b_type1                0.211076555
b_type2               0.874357977
b_type3                 0.416189508
b_emission_reduction 0.008422197

Running Delta method computations
                                                      Value Robust s.e. Rob t-ratio (0)
Ratio of b_time (multiplied by 60) and b_fare:    179       13.59           13.17

Results for Upper class

Code: Select all

Model name                                  : MNL_data_6min_UPP_ASC
Model description                           : MNL model on main data 6min  no filter WITH ASC for Upper class
Model run at                                : 2023-05-03 15:43:41
Estimation method                           : bfgs
Model diagnosis                             : successful convergence 
Number of individuals                       : 1863
Number of rows in database                  : 16767
Number of modelled outcomes                 : 16767

Number of cores used                        :  1 
Model without mixing

LL(start)                                   : -18420.43
LL at equal shares, LL(0)                   : -18420.43
LL at observed shares, LL(C)                : -17875.5
LL(final)                                   : -15858.61
Rho-squared vs equal shares                  :  0.1391 
Adj.Rho-squared vs equal shares              :  0.1386 
Rho-squared vs observed shares               :  0.1128 
Adj.Rho-squared vs observed shares           :  0.1124 
AIC                                         :  31733.22 
BIC                                         :  31795.03 

Estimated parameters                        :  8
Time taken (hh:mm:ss)                       :  00:00:4.22 
     pre-estimation                         :  00:00:0.97 
     estimation                             :  00:00:1.79 
     post-estimation                        :  00:00:1.47 
Iterations                                  :  17  
Min abs eigenvalue of Hessian               :  97.41227 

Unconstrained optimisation.

These outputs have had the scaling used in estimation applied to
  them.
Estimates:
                        Estimate        s.e.   t.rat.(0)    Rob.s.e.
ASC1                    0.164729    0.023226       7.092    0.021371
ASC2                    0.117621    0.023549       4.995    0.024336
ASC3                    0.000000          NA          NA          NA
b_fare                 -0.001491   4.322e-05     -34.488   4.785e-05
b_time           -0.019791    0.001089     -18.182    0.001208
b_type1                  0.826075    0.042013      19.662    0.045773
b_type2                     1.108554    0.077002      14.396    0.082995
b_type3                   1.140216    0.064496      17.679    0.072445
b_type0                0.000000          NA          NA          NA
b_emission_reduction    0.006725  5.5229e-04      12.176  5.7952e-04
                     Rob.t.rat.(0)
ASC1                         7.708
ASC2                         4.833
ASC3                            NA
b_fare                     -31.154
b_time               -16.387
b_type1                        18.047
b_type2                      13.357
b_type3                    15.739
b_type0                        NA
b_emission_reduction        11.604


Overview of choices for MNL model component :
                                     alt1    alt2     alt3
Times available                  16767.00 16767.0 16767.00
Times chosen                      6114.00  6959.0  3694.00
Percentage chosen overall           36.46    41.5    22.03
Percentage chosen when available    36.46    41.5    22.03


Classical covariance matrix:
                                     ASC1                 ASC2
ASC1                           5.3945e-04           3.5920e-04
ASC2                           3.5920e-04           5.5456e-04
b_fare                          1.008e-07            7.686e-08
b_time                    4.505e-07           -1.303e-06
b_type1                         -1.6353e-04          -2.0882e-04
b_type2                     -2.2397e-04          -1.7022e-04
b_type3                      -1.3298e-04          -1.2679e-04
b_emission_reduction            4.692e-08           -2.921e-07
                                   b_fare         b_flighttime
ASC1                            1.008e-07            4.505e-07
ASC2                            7.686e-08           -1.303e-06
b_fare                          1.868e-09            3.493e-08
b_time                    3.493e-08            1.185e-06
b_type1                           -7.536e-07           -8.484e-06
b_type2                          -1.088e-06           -3.560e-05
b_type3                       -9.961e-07           -3.111e-05
b_emission_reduction           -7.045e-10           -2.721e-08
                                    b_SAF                 b_EA
ASC1                          -1.6353e-04          -2.2397e-04
ASC2                          -2.0882e-04          -1.7022e-04
b_fare                         -7.536e-07           -1.088e-06
b_time                   -8.484e-06           -3.560e-05
b_type1                            0.001765             0.002197
b_type2                             0.002197             0.005929
b_type3                         0.002108             0.004022
b_emission_reduction           -1.643e-05           -2.827e-05
                                     b_HA b_emission_reduction
ASC1                          -1.3298e-04            4.692e-08
ASC2                          -1.2679e-04           -2.921e-07
b_fare                         -9.961e-07           -7.045e-10
b_time                   -3.111e-05           -2.721e-08
b_type1                            0.002108           -1.643e-05
b_type2                        0.004022           -2.827e-05
b_type3                         0.004160           -2.790e-05
b_emission_reduction           -2.790e-05            3.050e-07

Robust covariance matrix:
                                     ASC1                 ASC2
ASC1                           4.5673e-04           3.4310e-04
ASC2                           3.4310e-04           5.9226e-04
b_fare                          4.013e-08           -7.586e-09
b_time                   -7.386e-07           -3.136e-06
b_type1                           -1.682e-05          -1.5396e-04
b_type2                           9.146e-06           -3.962e-06
b_type3                        4.883e-05           -1.829e-05
b_emission_reduction           -1.033e-06           -8.736e-07
                                   b_fare         b_flighttime
ASC1                            4.013e-08           -7.386e-07
ASC2                           -7.586e-09           -3.136e-06
b_fare                          2.289e-09            3.861e-08
b_time                    3.861e-08            1.459e-06
b_type1                           -7.297e-07           -1.306e-05
b_type2                     -1.301e-06           -4.761e-05
b_type3                       -1.105e-06           -4.243e-05
b_emission_reduction           -1.065e-09            1.208e-08
                                    b_SAF                 b_EA
ASC1                           -1.682e-05            9.146e-06
ASC2                          -1.5396e-04           -3.962e-06
b_fare                         -7.297e-07           -1.301e-06
b_time                   -1.306e-05           -4.761e-05
b_type1                             0.002095             0.002735
b_type2                      0.002735             0.006888
b_type3                          0.002666             0.005125
b_emission_reduction           -1.522e-05           -3.016e-05
                                     b_HA b_emission_reduction
ASC1                            4.883e-05           -1.033e-06
ASC2                           -1.829e-05           -8.736e-07
b_fare                         -1.105e-06           -1.065e-09
b_time                   -4.243e-05            1.208e-08
b_type1                             0.002666           -1.522e-05
b_type2                       0.005125           -3.016e-05
b_type3                         0.005248           -2.902e-05
b_emission_reduction           -2.902e-05            3.358e-07

Classical correlation matrix:
                                     ASC1                 ASC2
ASC1                             1.000000              0.65673
ASC2                             0.656725              1.00000
b_fare                           0.100457              0.07551
b_time                     0.017820             -0.05083
b_type1                            -0.167587             -0.21106
b_type2                       -0.125233             -0.09387
b_type3                        -0.088773             -0.08348
b_emission_reduction             0.003657             -0.02246
                                   b_fare         b_flighttime
ASC1                              0.10046              0.01782
ASC2                              0.07551             -0.05083
b_fare                            1.00000              0.74243
b_time                      0.74243              1.00000
b_type1                             -0.41500             -0.18552
b_type2                       -0.32683             -0.42476
b_type3                         -0.35732             -0.44319
b_emission_reduction             -0.02951             -0.04527
                                    b_SAF                 b_EA
ASC1                              -0.1676             -0.12523
ASC2                              -0.2111             -0.09387
b_fare                            -0.4150             -0.32683
b_time                      -0.1855             -0.42476
b_type1                               1.0000              0.67912
b_type2                         0.6791              1.00000
b_type3                           0.7778              0.80986
b_emission_reduction              -0.7083             -0.66472
                                     b_HA b_emission_reduction
ASC1                             -0.08877             0.003657
ASC2                             -0.08348            -0.022459
b_fare                           -0.35732            -0.029513
b_time                     -0.44319            -0.045268
b_type1                              0.77780            -0.708280
b_type2                        0.80986            -0.664722
b_type3                          1.00000            -0.783257
b_emission_reduction             -0.78326             1.000000

Robust correlation matrix:
                                     ASC1                 ASC2
ASC1                             1.000000             0.659681
ASC2                             0.659681             1.000000
b_fare                           0.039250            -0.006515
b_time                    -0.028617            -0.106698
b_type1                            -0.017192            -0.138207
b_type2                            0.005156            -0.001962
b_type3                         0.031542            -0.010375
b_emission_reduction            -0.083412            -0.061944
                                   b_fare         b_flighttime
ASC1                             0.039250             -0.02862
ASC2                            -0.006515             -0.10670
b_fare                           1.000000              0.66809
b_time                     0.668090              1.00000
b_type1                            -0.333165             -0.23622
b_type2                      -0.327611             -0.47495
b_type3                        -0.318792             -0.48491
b_emission_reduction            -0.038410              0.01726
                                    b_SAF                 b_EA
ASC1                             -0.01719             0.005156
ASC2                             -0.13821            -0.001962
b_fare                           -0.33317            -0.327611
b_time                     -0.23622            -0.474951
b_type1                              1.00000             0.719853
b_type2                             0.71985             1.000000
b_type3                          0.80393             0.852413
b_emission_reduction             -0.57358            -0.627158
                                     b_HA b_emission_reduction
ASC1                              0.03154             -0.08341
ASC2                             -0.01037             -0.06194
b_fare                           -0.31879             -0.03841
b_time                     -0.48491              0.01726
b_type1                              0.80393             -0.57358
b_type2                            0.85241             -0.62716
b_type3                          1.00000             -0.69132
b_emission_reduction             -0.69132              1.00000

 20 worst outliers in terms of lowest average per choice prediction:
   ID Avg prob per choice
 1378           0.1441980
  875           0.1580217
  156           0.1596559
  248           0.1596559
  255           0.1596559
 1811           0.1614643
 2512           0.1620763
  329           0.1623155
 2117           0.1624230
 3134           0.1644534
  225           0.1682671
  885           0.1747638
  739           0.1748051
 2075           0.1771145
 2356           0.1775844
   61           0.1818256
 1670           0.1832686
 2507           0.1840305
 3026           0.1844901
 2734           0.1854417

Changes in parameter estimates from starting values:
                         Initial    Estimate  Difference
ASC1                       0.000    0.164729    0.164729
ASC2                       0.000    0.117621    0.117621
ASC3                       0.000    0.000000    0.000000
b_fare                     0.000   -0.001491   -0.001491
b_time               0.000   -0.019791   -0.019791
b_type1                       0.000    0.826075    0.826075
b_type2                       0.000    1.108554    1.108554
b_type3                   0.000    1.140216    1.140216
b_type4                   0.000    0.000000    0.000000
b_emission_reduction       0.000    0.006725    0.006725

Settings and functions used in model definition:

apollo_control
--------------
                       Value                                            
modelName              "MNL_data_6min_UPP_ASC"                          
modelDescr             "MNL model on main data 6min  no filter WITH ASC for upper class"
indivID                "ID"                                             
outputDirectory        "output/"                                        
debug                  "FALSE"                                          
nCores                 "1"                                              
workInLogs             "FALSE"                                          
seed                   "13"                                             
mixing                 "FALSE"                                          
HB                     "FALSE"                                          
noValidation           "FALSE"                                          
noDiagnostics          "FALSE"                                          
calculateLLC           "TRUE"                                           
panelData              "TRUE"                                           
analyticGrad           "TRUE"                                           
analyticGrad_manualSet "FALSE"                                          

Hessian routines attempted
--------------
numerical jacobian of LL analytical gradient

Scaling in estimation
--------------
                           Value
ASC1                 0.164728891
ASC2                 0.117620487
b_fare               0.001490599
b_time         0.019791498
b_type1                0.826076410
b_type2            1.108553072
b_type3             1.140214886
b_emission_reduction 0.006724660

Scaling used in computing Hessian
--------------
                           Value
ASC1                 0.164728842
ASC2                 0.117620504
b_fare               0.001490603
b_time         0.019791406
b_type1                 0.826075059
b_type2                 1.108553812
b_type3                 1.140215530
b_emission_reduction 0.006724657

Running Delta method computations
                                                      Value Robust s.e.
Ratio of b_time (multiplied by 60) and b_fare:  796.6       36.83
                                                      Rob t-ratio (0)
Ratio of b_time (multiplied by 60) and b_fare:            21.63
I would greatly appreciate your help!
Many thanks,
Peggy
stephanehess
Site Admin
Posts: 998
Joined: 24 Apr 2020, 16:29

Re: Unreasonable VTT value in the segment

Post by stephanehess »

Peggy

this isn't an Apollo question per se. There could be many reasons for this, including differences in the samples, non-linearities, etc

Stephane
--------------------------------
Stephane Hess
www.stephanehess.me.uk
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