Predicting the Winner of March Madness 2017 using R, Python, and Machine Learning

This project was done using R and Python, and the results were used as a submission to Deloitte’s March Madness Data Crunch Competition. Team members: Luo Yi, Yufei Long, and Yuyang Yue. Check the GitHub for the code.

Of the 64 teams that competed, we predicted Gonzaga University to win. Unfortunately, they lost to University of North Carolina.

Methodology

  1. Data transformation
  2. Data exploration
    • Feature Correlation testing
    • Principal Component Analysis
  3. Feature Selection
  4. Model Testing
    • Decision Tree
    • Logistic Regression
    • Random Forest
  5. Results and other analysis

Data Transformation

The data that was used to train the initial model was from a data set that contained 2002-2016 team performance data, which included statistics, efficiency ratings, etc.,  from different sources. Each row was a game that consisted of two teams and their respective performance data. For the initial training of the models, we were instructed to use 2002-2013 data as the training set and 2014-2016 data as the testing set. After examining the data, we debated on what would be the way to use it. We finally decided on creating new relative variables that would reflect the difference/ratio of team 1 and team 2’s performance. Feature correlation testing was also done during this phase. The results supported the need for relative variables.

Features Correlation Heatmap (Original Features)

Data Exploration

After transformation, feature correlation testing was repeated. This time, results were much more favorable. The heat map below shows that the correlation between the new variables is acceptable.

Features Correlation Heatmap (New Features)

Principal Component Analysis was also performed on the new features. We hoped to show which features were the most influential, even before running any machine learning models. Imputation was done to deal with missing values. The thicker lines in the chart below signify a more influential link to the 8 new discriminant features. This, however, was used to understand the features more and wasn’t used as an input for all the models.

Feature Selection by PCA

Feature Selection

For this project, we opted to remove anything (aside from seed and distance from game location) that wasn’t a performance metric. Some of the variables that were discarded were ratings data since we believed that they were too subjective to be reliable indicators.

Model Testing

We used three models for this project: Decision Tree, Logistic Regression, and Random Forest.

Decision Tree – Results were less than favorable for this model. Overfitting occurred and we had to drop it.

Random Forest (R) – We decided to use the Random Forest model for 2 different reasons: the need to bypass overfitting restrictions and its democratic nature.

Predictor Importance
  • OOB Estimate of error rate: 26.9%
  • Error reduction plateaus at approx. 2,600 trees
  • Model Log-loss: 0.5556
  • Chart Legend:
    • Black:  Out-of-bag estimate of error rate
    • Green and Red: Class errors
Forest Error Performance

Logistic Regression (Python) – From PCA analysis and Random Forest Model, 5 features were selected for this model. 

Features Selected for Logistic Regression

Results and Other Analysis

Summary of Results

Running them against the testing set, we were able to get a higher accuracy for the Random Forest model. Log loss, which was also one of the key performance indicators for the competition, was relatively the same for the 2 models. That being said, Random Forest was chosen to run the new 2017 march madness data.

As previously mentioned, we had predicted Gonzaga University to win the tournament. We came really close though. It made a lot of sense because, compared to the other teams, Gonzaga was a frequent contender in March Madness.

One of the more interesting teams this season was the cinderella team, South Carolina. They had gone against expectations, and this is why we decided to analyze their journey even further.

In the 1st round, we were able to correctly predict that South Carolina was going to win. However, because we were using historical data, it was obvious that we were going to predict them to lose in the next stages, especially since they were going against stronger teams. Despite “water under the bridge” data, they were able to reach the Final 4.

Cinderella Team Win Rate by Stage

One of the questions that we wanted to attempt to answer was why they kept on winning. What was so different this year that they were able to surprise everyone?

One reason that we speculated about was the high performance of one of South Carolina’s players, Sindarius Thornwell. In the past years, he was averaging 11-13 pts per game. This year, he was dropping 21.4 pts per game. Moreover, in his last 5 appearances, his was able to increase this stat to 23.6 pts per game. Looking at the score difference of South Carolina’s games in March Madness, it is evident that he was very influential in the team’s success. One could even say that without his 23.6 pts per game, the turnout of their campaign would’ve been different. But hey, that’s just speculation.

Score Difference for Cinderella Team Matches

 

Sindarius Thornwell March Madness Stats

 

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