Chapter 1 Introduction

In 2020, we saw the first ever NBA season that held a play-in tournament for the final 8th seed in both conferences. While the tournament was fun to watch, it made me think about the objective of this project:

How does a play-in tournament effect the preseason playoff odds of teams?

The code for this project can be found in my Github Repository at

In this bookdown, I will analyze the probabilistic effects of a play-in tournament style through the following steps:

1) Create a game level win prob model

  • This model will only include preseason variables as it is designed to predict outcomes before the season starts.

2) Simulate a “fake” traditional 82-game schedule and calculate each team’s playoff probability

  • Simulation will be based on predicted win probabilities from the trained win prob model from step #1.

3) Simulate play-in tournament for seasons in step #2 that qualify for a play-in tournament and calculate each team’s playoff probability.

  • Play-in tournament only occurs for seasons where the #9 seed is 1 GB or less from the #8 seed. The #8 seed must win 1 game while the #9 seed must win 2 games to advance into the playoffs

4) Compare the playoff probabilities in step #2 to step #3.

  • This is where we will see the impact of a play-in tournament when compared to a traditional season set up.