1. SAS Homework 2 Review Decision trees
MIS2502
Data Analytics

2. SAS Homework 2 Review Decision Trees
Using Organics Data Set from exercise #1. If Organics is wrong then your Decision Tree will be wrong
Partition: 50% Training, 50% Validation
Add a Decision Tree using defaults (max number branches 2)
Evaluate default Decision Tree using Average Square Error
Add another Decision Tree but this time customize by changing the max number of branches from 2 to 3
Assess this Decision Tree using Average Square Error
Compare default Tree (2 branch max) to customized Tree (3 branch max) and determine which model is ‘better’
Answer some questions regarding the customized Decision Tree

3. Partition

4. Decision Tree – Diagram
Right Click> Run after adding objects
Difference is Maximum Branch

5. Assessing the 1st Decision Tree
2 branches
Age is 1st branch

6. Assessing the 1st Decision Tree using average square error subtree assessment plot
View>Model>Subtree Assessment Plot
The line is the Optimal Leaf count for that tree
Note the Leaf Count and the Validation: Average Square Error

7. Assessing the 2nd Decision Tree

8. Assessing the 2nd Decision Tree
Note change in average square error
In general, less error is better

9. What is the probability that a 39
What is the probability that a 39.5 year old male with an affluence grade of 15 buys organics ?
Age = 39.5,
AfflGrade > 11.5
Gender = M
Look at the ‘Validation’ stats
1 = buy, 0 = no buy
Navigating the Tree

10. In Class

11. In Class 1. Answers: a. 45.2% b. 66.0% c. 57.2% d. 48.2%
2. It means that for those people who made more than three donations, the region’s average median home value doesn’t make a difference in whether they make an additional donation.
3. Answers:
a. GiftCnt36 – Gift Count 36 Months; because it has the highest logworth value, which means it does the
best job of differentiating between future donors and non‐donors.
b. Gift Count 36 Months is the first variable chosen by SAS to split the tree.