This the RMarkdown file on the case study of Airlines mini project.

Read the dataset in R

airlines.df <- read.csv(paste("SixAirlinesDataV2.csv", sep=""))
View(airlines.df)

Summarize it

library(psych)
describe(airlines.df)
##                     vars   n    mean      sd  median trimmed     mad   min
## Airline*               1 458    3.01    1.65    2.00    2.89    1.48  1.00
## Aircraft*              2 458    1.67    0.47    2.00    1.71    0.00  1.00
## FlightDuration         3 458    7.58    3.54    7.79    7.57    4.81  1.25
## TravelMonth*           4 458    2.56    1.17    3.00    2.58    1.48  1.00
## IsInternational*       5 458    1.91    0.28    2.00    2.00    0.00  1.00
## SeatsEconomy           6 458  202.31   76.37  185.00  194.64   85.99 78.00
## SeatsPremium           7 458   33.65   13.26   36.00   33.35   11.86  8.00
## PitchEconomy           8 458   31.22    0.66   31.00   31.26    0.00 30.00
## PitchPremium           9 458   37.91    1.31   38.00   38.05    0.00 34.00
## WidthEconomy          10 458   17.84    0.56   18.00   17.81    0.00 17.00
## WidthPremium          11 458   19.47    1.10   19.00   19.53    0.00 17.00
## PriceEconomy          12 458 1327.08  988.27 1242.00 1244.40 1159.39 65.00
## PricePremium          13 458 1845.26 1288.14 1737.00 1799.05 1845.84 86.00
## PriceRelative         14 458    0.49    0.45    0.36    0.42    0.41  0.02
## SeatsTotal            15 458  235.96   85.29  227.00  228.73   90.44 98.00
## PitchDifference       16 458    6.69    1.76    7.00    6.76    0.00  2.00
## WidthDifference       17 458    1.63    1.19    1.00    1.53    0.00  0.00
## PercentPremiumSeats   18 458   14.65    4.84   13.21   14.31    2.68  4.71
##                         max   range  skew kurtosis    se
## Airline*               6.00    5.00  0.61    -0.95  0.08
## Aircraft*              2.00    1.00 -0.72    -1.48  0.02
## FlightDuration        14.66   13.41 -0.07    -1.12  0.17
## TravelMonth*           4.00    3.00 -0.14    -1.46  0.05
## IsInternational*       2.00    1.00 -2.91     6.50  0.01
## SeatsEconomy         389.00  311.00  0.72    -0.36  3.57
## SeatsPremium          66.00   58.00  0.23    -0.46  0.62
## PitchEconomy          33.00    3.00 -0.03    -0.35  0.03
## PitchPremium          40.00    6.00 -1.51     3.52  0.06
## WidthEconomy          19.00    2.00 -0.04    -0.08  0.03
## WidthPremium          21.00    4.00 -0.08    -0.31  0.05
## PriceEconomy        3593.00 3528.00  0.51    -0.88 46.18
## PricePremium        7414.00 7328.00  0.50     0.43 60.19
## PriceRelative          1.89    1.87  1.17     0.72  0.02
## SeatsTotal           441.00  343.00  0.70    -0.53  3.99
## PitchDifference       10.00    8.00 -0.54     1.78  0.08
## WidthDifference        4.00    4.00  0.84    -0.53  0.06
## PercentPremiumSeats   24.69   19.98  0.71     0.28  0.23

Generate boxplot for relative price for each pitch difference

boxplot(airlines.df$PriceRelative ~ airlines.df$PitchDifference, horizontal=TRUE,
        xlab = "Price Relative", ylab = "Pitch Difference",
        main = "Relative price changes according to pitch difference"
          )

Generate boxplot for relative price for each width difference

boxplot(airlines.df$PriceRelative ~ airlines.df$WidthDifference, horizontal=TRUE,
        xlab = "Price Relative", ylab = "Width Difference",
        main = "Relative price changes according to width difference"
          )

Generate boxplots for important variables to check their distributions individually

boxplot(airlines.df$FlightDuration, horizontal=TRUE,
        main="Flight duration of all airlines")

boxplot(airlines.df$SeatsEconomy, horizontal=TRUE,
        main="Seats Economy of all airlines")

boxplot(airlines.df$SeatsPremium, horizontal=TRUE,
        main="Seats Premium of all airlines")

boxplot(airlines.df$PriceEconomy, horizontal=TRUE,
        main="Price Economy of all airlines")

boxplot(airlines.df$PricePremium, horizontal=TRUE,
        main="Price Premium of all airlines")

boxplot(airlines.df$PriceRelative, horizontal=TRUE,
        main="Price Relative of all airlines")

boxplot(airlines.df$SeatsTotal, horizontal=TRUE,
        main="Total seats of all airlines")

Draw Scatter Plots to understand how are the variables correlated pair-wise

library(car)
## 
## Attaching package: 'car'
## The following object is masked from 'package:psych':
## 
##     logit
library(psych)
 scatterplotMatrix(formula = ~ FlightDuration + SeatsEconomy + PitchEconomy +                            WidthEconomy + PriceEconomy + PriceRelative, data = airlines.df,                      diagonal="histogram")
## Warning in smoother(x, y, col = col[2], log.x = FALSE, log.y = FALSE,
## spread = spread, : could not fit negative part of the spread
## Warning in smoother(x, y, col = col[2], log.x = FALSE, log.y = FALSE,
## spread = spread, : could not fit smooth

library(car)
library(psych)
 scatterplotMatrix(formula = ~ FlightDuration + SeatsPremium + PitchPremium +                            WidthPremium + PricePremium + PriceRelative, data = airlines.df,                      diagonal="histogram")
## Warning in smoother(x, y, col = col[2], log.x = FALSE, log.y = FALSE,
## spread = spread, : could not fit smooth

## Warning in smoother(x, y, col = col[2], log.x = FALSE, log.y = FALSE,
## spread = spread, : could not fit smooth

## Warning in smoother(x, y, col = col[2], log.x = FALSE, log.y = FALSE,
## spread = spread, : could not fit smooth

library(car)
library(psych)
 scatterplotMatrix(formula = ~ PriceRelative + PitchDifference +                            WidthDifference + PercentPremiumSeats, data = airlines.df,                            diagonal="histogram")

correlation

cor.test(airlines.df$PriceRelative, airlines.df$PitchDifference)
## 
##  Pearson's product-moment correlation
## 
## data:  airlines.df$PriceRelative and airlines.df$PitchDifference
## t = 11.331, df = 456, p-value < 2.2e-16
## alternative hypothesis: true correlation is not equal to 0
## 95 percent confidence interval:
##  0.3940262 0.5372817
## sample estimates:
##       cor 
## 0.4687302

As p<0.05, these 2 variables are strongly corelated.

cor.test(airlines.df$PriceRelative, airlines.df$WidthDifference)
## 
##  Pearson's product-moment correlation
## 
## data:  airlines.df$PriceRelative and airlines.df$WidthDifference
## t = 11.869, df = 456, p-value < 2.2e-16
## alternative hypothesis: true correlation is not equal to 0
## 95 percent confidence interval:
##  0.4125388 0.5528218
## sample estimates:
##       cor 
## 0.4858024

As p<0.05, these 2 variables are strongly corelated.

cor.test(airlines.df$PriceRelative, airlines.df$PercentPremiumSeats)
## 
##  Pearson's product-moment correlation
## 
## data:  airlines.df$PriceRelative and airlines.df$PercentPremiumSeats
## t = -3.496, df = 456, p-value = 0.0005185
## alternative hypothesis: true correlation is not equal to 0
## 95 percent confidence interval:
##  -0.24949885 -0.07098966
## sample estimates:
##        cor 
## -0.1615656

As p>0.05, these 2 variables are not corelated at all.

corrgram

library(corrgram)
corrgram(airlines.df, order=FALSE, 
         lower.panel=panel.shade,
         upper.panel=panel.pie, 
         diag.panel=panel.minmax,
         text.panel=panel.txt,
         main="Corrgram of airlines intercorrelations")

Linear Regression

Consider the followng Regression equation

PriceRelative = b0 + b1PitchDifference + b2WidthDifference

mn <- lm(PriceRelative ~ 
           PitchDifference 
         + WidthDifference, 
         data=airlines.df)
summary(mn)
## 
## Call:
## lm(formula = PriceRelative ~ PitchDifference + WidthDifference, 
##     data = airlines.df)
## 
## Residuals:
##      Min       1Q   Median       3Q      Max 
## -0.84163 -0.28484 -0.07241  0.17698  1.18778 
## 
## Coefficients:
##                 Estimate Std. Error t value Pr(>|t|)    
## (Intercept)     -0.10514    0.08304  -1.266 0.206077    
## PitchDifference  0.06019    0.01590   3.785 0.000174 ***
## WidthDifference  0.11621    0.02356   4.933 1.14e-06 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 0.3886 on 455 degrees of freedom
## Multiple R-squared:  0.2593, Adjusted R-squared:  0.2561 
## F-statistic: 79.65 on 2 and 455 DF,  p-value: < 2.2e-16

INFERENCE * An increase in PitchDifference by 1 unit, increases PriceRelative by $0.0602
* An increase in WidthDifference by 1 unit, increases PriceRelative by $0.1162
so these 2 x variables PitchDifference and WidthDifference explain the difference in the price between premium-economy airline ticket.

What are the beta coefficients of the model?

# beta coefficients
mn$coefficients
##     (Intercept) PitchDifference WidthDifference 
##     -0.10514235      0.06019158      0.11621441

What are the Confidence Intervals on the beta coefficients?

# confidence intervals
confint(mn)
##                       2.5 %     97.5 %
## (Intercept)     -0.26832278 0.05803808
## PitchDifference  0.02893838 0.09144479
## WidthDifference  0.06991835 0.16251047
# Visualize 
library(coefplot)
## Loading required package: ggplot2
## 
## Attaching package: 'ggplot2'
## The following objects are masked from 'package:psych':
## 
##     %+%, alpha
# 1. PitchDifference and WidthDifference are statistically significant
coefplot(mn, predictors=c("PitchDifference","WidthDifference"))

PitchDifference and WidthDifference are statistically significant, since their Confidence Inteval do not include 0.

Compare the actual PriceRelative with the fitted values given by the OLS model

# Compare the PriceRelative with the fitted values 

# Here is the actual PriceRelative
airlines.df$PriceRelative
##   [1] 0.38 0.38 0.38 0.38 0.67 0.67 0.67 1.03 1.03 0.75 0.75 0.56 0.26 0.52
##  [15] 0.52 0.52 0.38 0.38 0.38 0.34 0.34 0.34 0.33 0.33 0.33 0.35 0.33 0.33
##  [29] 0.34 0.34 0.34 0.42 0.42 0.42 0.42 0.65 0.65 0.65 0.24 0.24 0.24 0.24
##  [43] 0.17 0.17 0.17 0.08 0.08 0.08 0.52 0.52 0.52 1.03 0.36 0.36 0.36 0.34
##  [57] 0.34 0.34 0.21 0.21 0.61 0.73 0.73 0.73 0.73 0.39 0.39 0.39 0.39 0.26
##  [71] 0.26 0.26 0.10 0.09 0.08 0.07 0.07 0.07 0.04 0.04 0.03 1.07 1.07 1.07
##  [85] 1.07 0.40 0.40 0.40 0.40 0.48 0.48 0.48 0.48 0.33 0.33 0.33 0.26 0.09
##  [99] 0.49 0.49 0.49 0.49 0.91 0.91 0.91 0.91 0.47 0.47 0.47 1.27 1.27 0.36
## [113] 0.06 0.10 0.10 0.04 0.11 0.11 0.08 0.09 0.05 0.05 0.11 0.14 0.17 0.16
## [127] 0.15 0.07 0.17 0.18 0.14 0.13 0.16 0.18 0.18 0.25 0.20 0.26 0.19 0.23
## [141] 0.23 0.30 0.30 0.30 0.25 0.29 0.29 0.29 0.40 0.31 0.33 0.13 0.10 0.09
## [155] 0.06 1.82 1.82 1.82 1.82 1.73 1.73 1.73 1.38 0.97 0.97 0.97 0.97 0.91
## [169] 0.91 0.91 0.91 0.84 0.56 0.51 0.51 0.51 0.51 0.50 0.49 0.40 0.40 0.40
## [183] 0.40 0.26 0.46 0.46 0.38 0.38 0.38 0.30 1.08 1.08 1.08 1.08 1.03 1.03
## [197] 1.03 1.03 0.84 0.84 0.84 0.49 0.49 0.41 0.41 0.41 0.41 0.26 0.10 0.10
## [211] 0.10 1.56 1.17 0.63 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08
## [225] 0.08 0.07 0.07 0.07 0.07 0.07 0.04 0.03 0.03 0.03 0.03 0.03 0.03 0.03
## [239] 0.03 1.13 1.13 0.26 0.45 0.45 0.45 0.36 0.36 0.36 0.36 0.98 0.98 0.98
## [253] 0.33 0.33 0.33 0.33 0.36 0.36 0.36 1.13 0.42 0.42 0.42 0.40 0.40 0.40
## [267] 0.80 0.07 0.07 0.07 1.11 1.11 0.91 0.20 0.80 0.17 0.17 0.17 0.21 0.57
## [281] 0.14 0.14 0.12 0.12 0.12 0.11 0.11 0.11 0.11 0.11 0.11 0.10 0.10 0.10
## [295] 0.09 0.09 0.08 0.08 0.08 0.07 0.07 0.05 0.05 0.05 0.04 0.04 0.04 1.50
## [309] 0.96 0.82 0.42 0.42 0.40 0.38 1.11 0.83 0.83 0.77 0.60 0.60 0.60 0.55
## [323] 0.48 0.48 0.13 0.13 0.13 0.13 0.13 0.13 0.10 0.10 0.10 0.10 0.09 0.09
## [337] 0.09 0.09 0.36 0.36 0.36 0.08 0.07 0.07 0.07 0.07 0.04 0.04 0.04 0.03
## [351] 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03
## [365] 0.03 0.03 1.39 1.39 1.39 0.14 0.14 0.14 0.77 0.48 0.48 0.04 0.52 0.37
## [379] 1.89 1.89 1.89 1.87 1.67 1.64 1.53 1.29 1.26 1.26 1.26 1.11 1.11 1.11
## [393] 1.09 1.06 1.04 1.04 0.91 0.81 0.79 0.74 0.74 0.74 0.74 0.50 0.17 1.64
## [407] 1.64 1.44 0.56 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.61 0.61 0.61
## [421] 0.61 0.61 0.61 0.61 0.61 1.16 1.16 0.08 0.08 0.07 0.07 0.07 0.04 0.04
## [435] 0.04 0.04 0.03 0.03 0.02 1.71 1.68 1.68 1.30 1.30 1.30 1.30 1.22 1.07
## [449] 0.77 0.77 0.77 0.65 0.60 0.58 0.45 0.45 0.38 0.12
# Here is the PriceRelative, as predicted by the OLS model
fitted(mn)
##          1          2          3          4          5          6 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##          7          8          9         10         11         12 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##         13         14         15         16         17         18 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##         19         20         21         22         23         24 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##         25         26         27         28         29         30 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##         31         32         33         34         35         36 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##         37         38         39         40         41         42 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##         43         44         45         46         47         48 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##         49         50         51         52         53         54 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##         55         56         57         58         59         60 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##         61         62         63         64         65         66 
## 0.43241314 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 
##         67         68         69         70         71         72 
## 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 
##         73         74         75         76         77         78 
## 0.66484196 0.07543240 0.07543240 0.07543240 0.07543240 0.07543240 
##         79         80         81         82         83         84 
## 0.07543240 0.07543240 0.07543240 0.43241314 0.43241314 0.43241314 
##         85         86         87         88         89         90 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.96163112 
##         91         92         93         94         95         96 
## 0.96163112 0.96163112 0.96163112 0.96163112 0.96163112 0.96163112 
##         97         98         99        100        101        102 
## 0.96163112 0.01524082 0.43241314 0.43241314 0.43241314 0.43241314 
##        103        104        105        106        107        108 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##        109        110        111        112        113        114 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##        115        116        117        118        119        120 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##        121        122        123        124        125        126 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##        127        128        129        130        131        132 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##        133        134        135        136        137        138 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##        139        140        141        142        143        144 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##        145        146        147        148        149        150 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##        151        152        153        154        155        156 
## 0.43241314 0.07543240 0.07543240 0.07543240 0.07543240 0.66484196 
##        157        158        159        160        161        162 
## 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 
##        163        164        165        166        167        168 
## 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 
##        169        170        171        172        173        174 
## 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 
##        175        176        177        178        179        180 
## 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 
##        181        182        183        184        185        186 
## 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 
##        187        188        189        190        191        192 
## 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 
##        193        194        195        196        197        198 
## 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 
##        199        200        201        202        203        204 
## 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 
##        205        206        207        208        209        210 
## 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 0.66484196 
##        211        212        213        214        215        216 
## 0.66484196 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 
##        217        218        219        220        221        222 
## 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 
##        223        224        225        226        227        228 
## 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 
##        229        230        231        232        233        234 
## 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 
##        235        236        237        238        239        240 
## 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 0.43241314 
##        241        242        243        244        245        246 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##        247        248        249        250        251        252 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##        253        254        255        256        257        258 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##        259        260        261        262        263        264 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##        265        266        267        268        269        270 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##        271        272        273        274        275        276 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##        277        278        279        280        281        282 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.01524082 0.01524082 
##        283        284        285        286        287        288 
## 0.01524082 0.01524082 0.01524082 0.07543240 0.07543240 0.07543240 
##        289        290        291        292        293        294 
## 0.01524082 0.01524082 0.01524082 0.07543240 0.01524082 0.01524082 
##        295        296        297        298        299        300 
## 0.01524082 0.01524082 0.01524082 0.01524082 0.01524082 0.01524082 
##        301        302        303        304        305        306 
## 0.01524082 0.01524082 0.01524082 0.01524082 0.01524082 0.01524082 
##        307        308        309        310        311        312 
## 0.01524082 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 
##        313        314        315        316        317        318 
## 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 
##        319        320        321        322        323        324 
## 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 
##        325        326        327        328        329        330 
## 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 
##        331        332        333        334        335        336 
## 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 
##        337        338        339        340        341        342 
## 0.37222156 0.37222156 0.48843597 0.48843597 0.48843597 0.48843597 
##        343        344        345        346        347        348 
## 0.48843597 0.48843597 0.48843597 0.48843597 0.48843597 0.48843597 
##        349        350        351        352        353        354 
## 0.48843597 0.48843597 0.48843597 0.48843597 0.48843597 0.48843597 
##        355        356        357        358        359        360 
## 0.48843597 0.48843597 0.48843597 0.48843597 0.48843597 0.48843597 
##        361        362        363        364        365        366 
## 0.48843597 0.48843597 0.48843597 0.48843597 0.48843597 0.48843597 
##        367        368        369        370        371        372 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##        373        374        375        376        377        378 
## 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 0.43241314 
##        379        380        381        382        383        384 
## 0.96163112 0.96163112 0.96163112 0.96163112 0.96163112 0.96163112 
##        385        386        387        388        389        390 
## 0.96163112 0.96163112 0.96163112 0.96163112 0.96163112 0.96163112 
##        391        392        393        394        395        396 
## 0.96163112 0.96163112 0.96163112 0.96163112 0.96163112 0.96163112 
##        397        398        399        400        401        402 
## 0.96163112 0.96163112 0.96163112 0.96163112 0.96163112 0.96163112 
##        403        404        405        406        407        408 
## 0.96163112 0.96163112 0.96163112 0.48843597 0.48843597 0.48843597 
##        409        410        411        412        413        414 
## 0.48843597 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 
##        415        416        417        418        419        420 
## 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 
##        421        422        423        424        425        426 
## 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 
##        427        428        429        430        431        432 
## 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 
##        433        434        435        436        437        438 
## 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 0.37222156 
##        439        440        441        442        443        444 
## 0.37222156 0.96163112 0.96163112 0.96163112 0.96163112 0.96163112 
##        445        446        447        448        449        450 
## 0.96163112 0.96163112 0.96163112 0.96163112 0.96163112 0.96163112 
##        451        452        453        454        455        456 
## 0.96163112 0.96163112 0.96163112 0.96163112 0.96163112 0.96163112 
##        457        458 
## 0.96163112 0.96163112
# Compare PriceRelative predicted by the model with the actual PriceRelative given in the data
predictedPriceRelative = data.frame(fitted(mn)) 
actualPriceRelative = data.frame(airlines.df$PriceRelative)
PriceRelativeComparison = cbind(actualPriceRelative, predictedPriceRelative)
View(PriceRelativeComparison)