Assignment 8

Objective

Predict cheaters using the Affairs data from the AER package, using the classification algorithm from the rpart package.

Data Prep

• Created a new binary variable cheater by classifying observations with 0 affairs as 0, and with one or more affairs as 1.
• Split the data (601 observations), into training and validation datasets (70%/30% , 425/176)

The Tree

Two Interpretations from the Tree

1. The most likely cheaters:
   • been married more that 2.8 years
   • Not very religious (religiousness < 4)
   • Educated (education > = 17 years)
   • Rates their marriage not so well (rating < 4)
2. Unlikely cheater

• Newlywed (years married < 2.8 years)

Variable Importance

Interesting how gender is perceived by many as a predictor for cheating. However, the data shows that it is not a good predictor

Model Accuracy

Using the validation data, it is observed that the model is able to:

• Predict correctly 27% of the cheaters
• Misclassify faithful people as cheaters 8.6% of the time

## 
##  
##    Cell Contents
## |-------------------------|
## |                       N |
## | Chi-square contribution |
## |           N / Row Total |
## |           N / Col Total |
## |         N / Table Total |
## |-------------------------|
## 
##  
## Total Observations in Table:  2990 
## 
##  
##                                     | validation_tree$atrittion_predicted 
## validation_tree$atrittion_predicted | Attrited Customer | Existing Customer |         Row Total | 
## ------------------------------------|-------------------|-------------------|-------------------|
##                   Attrited Customer |               454 |                 0 |               454 | 
##                                     |          2150.935 |           385.065 |                   | 
##                                     |             1.000 |             0.000 |             0.152 | 
##                                     |             1.000 |             0.000 |                   | 
##                                     |             0.152 |             0.000 |                   | 
## ------------------------------------|-------------------|-------------------|-------------------|
##                   Existing Customer |                 0 |              2536 |              2536 | 
##                                     |           385.065 |            68.935 |                   | 
##                                     |             0.000 |             1.000 |             0.848 | 
##                                     |             0.000 |             1.000 |                   | 
##                                     |             0.000 |             0.848 |                   | 
## ------------------------------------|-------------------|-------------------|-------------------|
##                        Column Total |               454 |              2536 |              2990 | 
##                                     |             0.152 |             0.848 |                   | 
## ------------------------------------|-------------------|-------------------|-------------------|
## 
##  
## Statistics for All Table Factors
## 
## 
## Pearson's Chi-squared test 
## ------------------------------------------------------------
## Chi^2 =  2990     d.f. =  1     p =  0 
## 
## Pearson's Chi-squared test with Yates' continuity correction 
## ------------------------------------------------------------
## Chi^2 =  2982.24     d.f. =  1     p =  0 
## 
##