R Markdown

airline.df<-read.csv(paste("SixAirlinesDataV2.csv", sep=""))
summary(airline.df)
##       Airline      Aircraft   FlightDuration   TravelMonth
##  AirFrance: 74   AirBus:151   Min.   : 1.250   Aug:127    
##  British  :175   Boeing:307   1st Qu.: 4.260   Jul: 75    
##  Delta    : 46                Median : 7.790   Oct:127    
##  Jet      : 61                Mean   : 7.578   Sep:129    
##  Singapore: 40                3rd Qu.:10.620              
##  Virgin   : 62                Max.   :14.660              
##       IsInternational  SeatsEconomy    SeatsPremium    PitchEconomy  
##  Domestic     : 40    Min.   : 78.0   Min.   : 8.00   Min.   :30.00  
##  International:418    1st Qu.:133.0   1st Qu.:21.00   1st Qu.:31.00  
##                       Median :185.0   Median :36.00   Median :31.00  
##                       Mean   :202.3   Mean   :33.65   Mean   :31.22  
##                       3rd Qu.:243.0   3rd Qu.:40.00   3rd Qu.:32.00  
##                       Max.   :389.0   Max.   :66.00   Max.   :33.00  
##   PitchPremium    WidthEconomy    WidthPremium    PriceEconomy 
##  Min.   :34.00   Min.   :17.00   Min.   :17.00   Min.   :  65  
##  1st Qu.:38.00   1st Qu.:18.00   1st Qu.:19.00   1st Qu.: 413  
##  Median :38.00   Median :18.00   Median :19.00   Median :1242  
##  Mean   :37.91   Mean   :17.84   Mean   :19.47   Mean   :1327  
##  3rd Qu.:38.00   3rd Qu.:18.00   3rd Qu.:21.00   3rd Qu.:1909  
##  Max.   :40.00   Max.   :19.00   Max.   :21.00   Max.   :3593  
##   PricePremium    PriceRelative      SeatsTotal  PitchDifference 
##  Min.   :  86.0   Min.   :0.0200   Min.   : 98   Min.   : 2.000  
##  1st Qu.: 528.8   1st Qu.:0.1000   1st Qu.:166   1st Qu.: 6.000  
##  Median :1737.0   Median :0.3650   Median :227   Median : 7.000  
##  Mean   :1845.3   Mean   :0.4872   Mean   :236   Mean   : 6.688  
##  3rd Qu.:2989.0   3rd Qu.:0.7400   3rd Qu.:279   3rd Qu.: 7.000  
##  Max.   :7414.0   Max.   :1.8900   Max.   :441   Max.   :10.000  
##  WidthDifference PercentPremiumSeats
##  Min.   :0.000   Min.   : 4.71      
##  1st Qu.:1.000   1st Qu.:12.28      
##  Median :1.000   Median :13.21      
##  Mean   :1.633   Mean   :14.65      
##  3rd Qu.:3.000   3rd Qu.:15.36      
##  Max.   :4.000   Max.   :24.69

Including Plots

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## Warning: package 'caTools' was built under R version 3.4.3
##       Airline Aircraft FlightDuration TravelMonth IsInternational
## 2     British   Boeing          12.25         Aug   International
## 15    British   Boeing          11.58         Sep   International
## 16    British   Boeing          11.58         Oct   International
## 19    British   Boeing           9.16         Oct   International
## 26    British   Boeing           8.75         Aug   International
## 28    British   Boeing           8.75         Oct   International
## 37    British   Boeing          13.50         Sep   International
## 42    British   Boeing           3.83         Oct   International
## 50    British   Boeing          12.75         Sep   International
## 53    British   Boeing          11.08         Aug   International
## 54    British   Boeing          11.08         Sep   International
## 55    British   Boeing          11.08         Oct   International
## 56    British   Boeing           6.08         Aug   International
## 61    British   Boeing          12.50         Oct   International
## 64     Virgin   AirBus           8.00         Sep   International
## 73     Virgin   AirBus           7.75         Aug   International
## 78      Delta   Boeing           2.33         Oct        Domestic
## 83    British   Boeing           6.83         Aug   International
## 85    British   Boeing           6.83         Oct   International
## 87    British   Boeing           7.58         Sep   International
## 94        Jet   Boeing           3.08         Aug   International
## 101   British   AirBus          11.16         Sep   International
## 102   British   AirBus          11.16         Oct   International
## 103   British   AirBus          10.50         Jul   International
## 108   British   AirBus          13.08         Sep   International
## 110   British   AirBus          11.16         Sep   International
## 114   British   AirBus           3.58         Aug   International
## 115   British   AirBus           3.58         Sep   International
## 119   British   AirBus           3.58         Aug   International
## 123   British   AirBus           2.41         Aug   International
## 124   British   AirBus           3.25         Oct   International
## 130   British   AirBus           1.83         Aug   International
## 144   British   Boeing           1.25         Sep   International
## 146   British   AirBus           2.83         Oct   International
## 151   British   Boeing           1.33         Oct   International
## 153     Delta   Boeing           4.51         Aug        Domestic
## 154     Delta   Boeing           4.33         Jul        Domestic
## 155     Delta   Boeing           4.51         Jul        Domestic
## 160    Virgin   Boeing          12.08         Aug   International
## 165    Virgin   Boeing           9.91         Aug   International
## 166    Virgin   Boeing           9.91         Sep   International
## 169    Virgin   Boeing          10.83         Aug   International
## 170    Virgin   Boeing          10.83         Sep   International
## 173    Virgin   Boeing          12.58         Aug   International
## 175    Virgin   Boeing          10.75         Aug   International
## 177    Virgin   Boeing          10.75         Oct   International
## 179    Virgin   Boeing          11.33         Oct   International
## 184    Virgin   Boeing          12.58         Sep   International
## 194    Virgin   AirBus           6.91         Oct   International
## 196    Virgin   AirBus           6.58         Aug   International
## 201    Virgin   AirBus          10.41         Sep   International
## 210    Virgin   AirBus           7.75         Sep   International
## 217 AirFrance   AirBus           8.33         Sep   International
## 218 AirFrance   AirBus           8.33         Oct   International
## 220 AirFrance   AirBus           8.33         Aug   International
## 221 AirFrance   AirBus           8.33         Sep   International
## 227 AirFrance   AirBus           6.83         Oct   International
## 231 AirFrance   AirBus           8.08         Sep   International
## 240   British   Boeing          10.41         Aug   International
## 246   British   Boeing           9.91         Jul   International
## 252   British   Boeing           8.58         Oct   International
## 261   British   Boeing           8.66         Aug   International
## 262   British   Boeing           8.66         Sep   International
## 265   British   Boeing           7.25         Sep   International
## 268   British   Boeing           7.08         Aug   International
## 270   British   Boeing           7.08         Oct   International
## 278   British   Boeing          11.08         Sep   International
## 283     Delta   Boeing           4.63         Aug        Domestic
## 284     Delta   Boeing           4.65         Sep        Domestic
## 285     Delta   Boeing           4.66         Oct        Domestic
## 286     Delta   Boeing           4.70         Jul        Domestic
## 289     Delta   Boeing           4.36         Sep        Domestic
## 296     Delta   AirBus           1.95         Sep        Domestic
## 297     Delta   AirBus           2.26         Sep        Domestic
## 298     Delta   AirBus           2.55         Oct        Domestic
## 313       Jet   AirBus           9.50         Sep   International
## 314       Jet   AirBus           8.91         Aug   International
## 320 Singapore   Boeing          12.41         Sep   International
## 321 Singapore   Boeing          12.41         Oct   International
## 325 Singapore   Boeing          14.66         Aug   International
## 331 Singapore   Boeing           3.83         Jul   International
## 333 Singapore   Boeing           3.83         Sep   International
## 336 Singapore   Boeing          12.75         Sep   International
## 342 AirFrance   Boeing           7.50         Oct   International
## 343 AirFrance   Boeing           6.83         Aug   International
## 353 AirFrance   Boeing           9.50         Oct   International
## 355 AirFrance   Boeing           7.75         Aug   International
## 358 AirFrance   Boeing           9.41         Aug   International
## 360 AirFrance   Boeing           9.41         Oct   International
## 364 AirFrance   Boeing          11.91         Aug   International
## 367   British   Boeing          13.83         Aug   International
## 370   British   Boeing          13.33         Aug   International
## 372   British   Boeing          13.33         Oct   International
## 377   British   Boeing           9.58         Oct   International
## 383       Jet   Boeing           3.25         Oct   International
## 389       Jet   Boeing           2.50         Oct   International
## 390       Jet   Boeing           2.66         Jul   International
## 396       Jet   Boeing           4.16         Oct   International
## 399       Jet   Boeing           2.66         Aug   International
## 405       Jet   Boeing           3.25         Jul   International
## 407 AirFrance   Boeing           6.91         Oct   International
## 410 Singapore   AirBus          13.33         Jul   International
## 418 Singapore   AirBus          12.66         Jul   International
## 423 Singapore   AirBus           6.50         Aug   International
## 424 Singapore   AirBus           6.50         Sep   International
## 426 AirFrance   AirBus          13.00         Sep   International
## 432 AirFrance   Boeing          10.66         Oct   International
## 435 AirFrance   AirBus           8.50         Sep   International
## 436 AirFrance   Boeing           8.50         Oct   International
## 441       Jet   Boeing           3.16         Jul   International
## 443       Jet   Boeing           5.66         Jul   International
## 444       Jet   Boeing           5.66         Aug   International
## 447       Jet   Boeing           5.66         Jul   International
## 450       Jet   Boeing           2.58         Sep   International
## 453       Jet   Boeing           2.58         Jul   International
##     SeatsEconomy SeatsPremium PitchEconomy PitchPremium WidthEconomy
## 2            122           40           31           38           18
## 15           122           40           31           38           18
## 16           122           40           31           38           18
## 19           122           40           31           38           18
## 26           122           40           31           38           18
## 28           122           40           31           38           18
## 37           122           40           31           38           18
## 42           122           40           31           38           18
## 50           122           40           31           38           18
## 53           127           39           31           38           18
## 54           127           39           31           38           18
## 55           127           39           31           38           18
## 56           127           39           31           38           18
## 61           127           39           31           38           18
## 64           185           48           31           38           18
## 73           185           48           31           38           18
## 78            78           20           31           34           18
## 83           243           56           31           38           18
## 85           243           56           31           38           18
## 87           243           56           31           38           18
## 94           138           28           30           40           17
## 101          303           55           31           38           18
## 102          303           55           31           38           18
## 103          303           55           31           38           18
## 108          303           55           31           38           18
## 110          303           55           31           38           18
## 114          303           55           31           38           18
## 115          303           55           31           38           18
## 119          303           55           31           38           18
## 123          303           55           31           38           18
## 124          303           55           31           38           18
## 130          303           55           31           38           18
## 144          303           55           31           38           18
## 146          303           55           31           38           18
## 151          303           55           31           38           18
## 153          171           29           32           35           18
## 154          171           29           32           35           18
## 155          171           29           32           35           18
## 160          198           35           31           38           18
## 165          375           66           31           38           18
## 166          375           66           31           38           18
## 169          198           35           31           38           18
## 170          198           35           31           38           18
## 173          198           35           31           38           18
## 175          375           66           31           38           18
## 177          375           66           31           38           18
## 179          198           35           31           38           18
## 184          198           35           31           38           18
## 194          233           38           31           38           18
## 196          233           38           31           38           18
## 201          233           38           31           38           18
## 210          233           38           31           38           18
## 217          147           21           32           38           18
## 218          147           21           32           38           18
## 220          147           21           32           38           18
## 221          147           21           32           38           18
## 227          147           21           32           38           18
## 231          147           21           32           38           18
## 240          243           36           31           38           18
## 246          243           36           31           38           18
## 252          243           36           31           38           18
## 261          243           36           31           38           18
## 262          243           36           31           38           18
## 265          243           36           31           38           18
## 268          243           36           31           38           18
## 270          243           36           31           38           18
## 278          243           36           31           38           18
## 283          126           18           32           34           17
## 284          126           18           32           34           17
## 285          126           18           32           34           17
## 286          139           21           31           34           17
## 289          126           18           32           34           17
## 296          120           18           32           34           17
## 297          120           18           32           34           17
## 298          136           20           33           35           17
## 313          147           21           32           38           18
## 314          147           21           32           38           18
## 320          184           28           32           38           19
## 321          184           28           32           38           19
## 325          184           28           32           38           19
## 331          184           28           32           38           19
## 333          184           28           32           38           19
## 336          184           28           32           38           19
## 342          200           28           32           38           17
## 343          200           28           32           38           17
## 353          200           28           32           38           17
## 355          174           24           32           38           17
## 358          200           28           32           38           17
## 360          200           28           32           38           17
## 364          200           28           32           38           17
## 367          203           24           31           38           18
## 370          203           24           31           38           18
## 372          203           24           31           38           18
## 377          203           24           31           38           18
## 383          124           16           30           40           17
## 389          124           16           30           40           17
## 390          124           16           30           40           17
## 396          124           16           30           40           17
## 399          124           16           30           40           17
## 405          124           16           30           40           17
## 407          216           24           32           38           17
## 410          333           36           32           38           19
## 418          333           36           32           38           19
## 423          333           36           32           38           19
## 424          333           36           32           38           19
## 426          389           38           32           38           18
## 432          389           38           32           38           18
## 435          389           38           32           38           18
## 436          389           38           32           38           18
## 441          162            8           30           40           17
## 443          162            8           30           40           17
## 444          162            8           30           40           17
## 447          162            8           30           40           17
## 450          162            8           30           40           17
## 453          162            8           30           40           17
##     WidthPremium PriceEconomy PricePremium PriceRelative SeatsTotal
## 2             19         2707         3725          0.38        162
## 15            19         1750         2656          0.52        162
## 16            19         1750         2656          0.52        162
## 19            19         1813         2504          0.38        162
## 26            19         1542         2084          0.35        162
## 28            19         1566         2084          0.33        162
## 37            19          940         1548          0.65        162
## 42            19         1224         1512          0.24        162
## 50            19          509          773          0.52        162
## 53            19         2156         2933          0.36        166
## 54            19         2156         2933          0.36        166
## 55            19         2156         2933          0.36        166
## 56            19         1634         2195          0.34        166
## 61            19          509          818          0.61        166
## 64            21         1813         3128          0.73        233
## 73            21          540          594          0.10        233
## 78            18          216          231          0.07         98
## 83            19         1444         2982          1.07        299
## 85            19         1444         2982          1.07        299
## 87            19         1824         2549          0.40        299
## 94            21          464          616          0.33        166
## 101           19         2384         3563          0.49        358
## 102           19         2384         3563          0.49        358
## 103           19         1848         3536          0.91        358
## 108           19         1758         2592          0.47        358
## 110           19          719         1634          1.27        358
## 114           19          402          442          0.10        358
## 115           19          402          442          0.10        358
## 119           19          322          348          0.08        358
## 123           19          276          306          0.11        358
## 124           19          249          285          0.14        358
## 130           19          201          237          0.18        358
## 144           19          109          141          0.30        358
## 146           19           97          125          0.29        358
## 151           19           65           86          0.33        358
## 153           18          423          467          0.10        200
## 154           18          483          527          0.09        200
## 155           18          713          757          0.06        200
## 160           21         1086         2964          1.73        233
## 165           21         1781         3509          0.97        441
## 166           21         1781         3509          0.97        441
## 169           21         1580         3019          0.91        233
## 170           21         1580         3019          0.91        233
## 173           21         1096         1710          0.56        233
## 175           21         2445         3694          0.51        441
## 177           21         2445         3694          0.51        441
## 179           21         2369         3540          0.49        233
## 184           21         1356         1710          0.26        233
## 194           21         1434         2982          1.08        271
## 196           21         1476         2997          1.03        271
## 201           21         1903         3509          0.84        271
## 210           21          540          594          0.10        271
## 217           19         2659         2859          0.08        168
## 218           19         2659         2859          0.08        168
## 220           19         2659         2859          0.08        168
## 221           19         2659         2859          0.08        168
## 227           19         2860         3063          0.07        168
## 231           19         2813         2922          0.04        168
## 240           19         1651         3509          1.13        279
## 246           19         2356         3200          0.36        279
## 252           19         1562         3099          0.98        279
## 261           19         1609         2292          0.42        279
## 262           19         1609         2292          0.42        279
## 265           19         1632         2278          0.40        279
## 268           19         1736         1866          0.07        279
## 270           19         1736         1866          0.07        279
## 278           19         1023         1199          0.17        279
## 283           17          363          407          0.12        144
## 284           17          363          407          0.12        144
## 285           17          363          407          0.12        144
## 286           17          413          457          0.11        160
## 289           17          413          457          0.11        144
## 296           17          166          181          0.09        138
## 297           17          329          354          0.08        138
## 298           17          243          262          0.08        156
## 313           19          661          928          0.40        168
## 314           19          676          931          0.38        168
## 320           20         1215         1947          0.60        212
## 321           20         1215         1947          0.60        212
## 325           20         1406         1584          0.13        212
## 331           20          563          619          0.10        212
## 333           20          563          619          0.10        212
## 336           20         1431         1564          0.09        212
## 342           19         2581         2781          0.08        228
## 343           19         2860         3063          0.07        228
## 353           19         3414         3524          0.03        228
## 355           19         3215         3325          0.03        198
## 358           19         3480         3589          0.03        228
## 360           19         3480         3589          0.03        228
## 364           19         3159         3243          0.03        228
## 367           19         3102         7414          1.39        227
## 370           19         2166         2470          0.14        227
## 372           19         2166         2470          0.14        227
## 377           19          524          797          0.52        227
## 383           21          149          398          1.67        140
## 389           21          118          267          1.26        140
## 390           21          108          228          1.11        140
## 396           21          156          318          1.04        140
## 399           21          127          228          0.79        140
## 405           21          594          696          0.17        140
## 407           19          648         1710          1.64        240
## 410           20          505         1004          0.99        369
## 418           20          690         1110          0.61        369
## 423           20          690         1110          0.61        369
## 424           20          690         1110          0.61        369
## 426           19         1522         3289          1.16        427
## 432           19         2996         3196          0.07        427
## 435           19         2979         3088          0.04        427
## 436           19         2979         3088          0.04        427
## 441           21          148          397          1.68        170
## 443           21          187          430          1.30        170
## 444           21          187          430          1.30        170
## 447           21          245          545          1.22        170
## 450           21          172          304          0.77        170
## 453           21          281          451          0.60        170
##     PitchDifference WidthDifference PercentPremiumSeats
## 2                 7               1               24.69
## 15                7               1               24.69
## 16                7               1               24.69
## 19                7               1               24.69
## 26                7               1               24.69
## 28                7               1               24.69
## 37                7               1               24.69
## 42                7               1               24.69
## 50                7               1               24.69
## 53                7               1               23.49
## 54                7               1               23.49
## 55                7               1               23.49
## 56                7               1               23.49
## 61                7               1               23.49
## 64                7               3               20.60
## 73                7               3               20.60
## 78                3               0               20.41
## 83                7               1               18.73
## 85                7               1               18.73
## 87                7               1               18.73
## 94               10               4               16.87
## 101               7               1               15.36
## 102               7               1               15.36
## 103               7               1               15.36
## 108               7               1               15.36
## 110               7               1               15.36
## 114               7               1               15.36
## 115               7               1               15.36
## 119               7               1               15.36
## 123               7               1               15.36
## 124               7               1               15.36
## 130               7               1               15.36
## 144               7               1               15.36
## 146               7               1               15.36
## 151               7               1               15.36
## 153               3               0               14.50
## 154               3               0               14.50
## 155               3               0               14.50
## 160               7               3               15.02
## 165               7               3               14.97
## 166               7               3               14.97
## 169               7               3               15.02
## 170               7               3               15.02
## 173               7               3               15.02
## 175               7               3               14.97
## 177               7               3               14.97
## 179               7               3               15.02
## 184               7               3               15.02
## 194               7               3               14.02
## 196               7               3               14.02
## 201               7               3               14.02
## 210               7               3               14.02
## 217               6               1               12.50
## 218               6               1               12.50
## 220               6               1               12.50
## 221               6               1               12.50
## 227               6               1               12.50
## 231               6               1               12.50
## 240               7               1               12.90
## 246               7               1               12.90
## 252               7               1               12.90
## 261               7               1               12.90
## 262               7               1               12.90
## 265               7               1               12.90
## 268               7               1               12.90
## 270               7               1               12.90
## 278               7               1               12.90
## 283               2               0               12.50
## 284               2               0               12.50
## 285               2               0               12.50
## 286               3               0               13.13
## 289               2               0               12.50
## 296               2               0               13.04
## 297               2               0               13.04
## 298               2               0               12.82
## 313               6               1               12.50
## 314               6               1               12.50
## 320               6               1               13.21
## 321               6               1               13.21
## 325               6               1               13.21
## 331               6               1               13.21
## 333               6               1               13.21
## 336               6               1               13.21
## 342               6               2               12.28
## 343               6               2               12.28
## 353               6               2               12.28
## 355               6               2               12.12
## 358               6               2               12.28
## 360               6               2               12.28
## 364               6               2               12.28
## 367               7               1               10.57
## 370               7               1               10.57
## 372               7               1               10.57
## 377               7               1               10.57
## 383              10               4               11.43
## 389              10               4               11.43
## 390              10               4               11.43
## 396              10               4               11.43
## 399              10               4               11.43
## 405              10               4               11.43
## 407               6               2               10.00
## 410               6               1                9.76
## 418               6               1                9.76
## 423               6               1                9.76
## 424               6               1                9.76
## 426               6               1                8.90
## 432               6               1                8.90
## 435               6               1                8.90
## 436               6               1                8.90
## 441              10               4                4.71
## 443              10               4                4.71
## 444              10               4                4.71
## 447              10               4                4.71
## 450              10               4                4.71
## 453              10               4                4.71

The reason that you may not see all the variables in the output of the tree is because they don’t have a significant influence on the dependend variable. Unlike linear or logistic regression, that will show all the variables and give you the P-value in order to determine if they are significant or not, the decision tree does not return the unsiginifcant variables, i.e, it doesn’t split by them.

library(party)
## Warning: package 'party' was built under R version 3.4.3
## Loading required package: grid
## Loading required package: mvtnorm
## Loading required package: modeltools
## Loading required package: stats4
## Loading required package: strucchange
## Warning: package 'strucchange' was built under R version 3.4.3
## Loading required package: zoo
## Warning: package 'zoo' was built under R version 3.4.3
## 
## Attaching package: 'zoo'
## The following objects are masked from 'package:base':
## 
##     as.Date, as.Date.numeric
## Loading required package: sandwich
## Warning: package 'sandwich' was built under R version 3.4.3
output.tree<-ctree(PriceEconomy~PercentPremiumSeats+PitchDifference+WidthDifference, data=airline.df)
plot(output.tree)

output.tree<-ctree(PricePremium~PercentPremiumSeats+PitchDifference+WidthDifference, data=airline.df)
plot(output.tree)

output.tree<-ctree(PricePremium~PercentPremiumSeats+SeatsTotal+SeatsPremium, data=airline.df)
plot(output.tree)

No significant correlation, hence, no split.

output.tree<-ctree(PriceEconomy~WidthDifference, data=airline.df)
plot(output.tree)

RELAX CRITERION So, the case weight is simply a vector indicating if an observation is in a node or in a particular final cell (final cell can be read as ‘terminal node’) of the partition space. The sum of case weights in a terminal node is the same as how many observations are in that final cell. Note that the length of the case weight vector is equal to the number of records. 1)mincriterion the value of the test statistic (for testtype == “Teststatistic”), or 1 - p-value (for other values of testtype) that must be exceeded in order to implement a split. 2)minsplit the minimum sum of weights in a node in order to be considered for splitting. 3)minbucket the minimum sum of weights in a terminal node.

output.tree<-ctree(PriceEconomy~WidthDifference, data=airline.df, controls=ctree_control(mincriterion = 0.01, minsplit=5, minbucket=1))
plot(output.tree)

output.tree<-ctree(PriceEconomy~PercentPremiumSeats, data=airline.df, controls=ctree_control(mincriterion = 0.7, minsplit=5, minbucket=1))
plot(output.tree)

Note that the echo = FALSE parameter was added to the code chunk to prevent printing of the R code that generated the plot.