1. Contributed by James Hedges and Malcolm Hess.
2. James and Malcolm are part of the 12-Week Data Science Bootcamp with Vivian Zhang in the spring of 2015.
3. This post is based on their first in-class presentation, a review of Benjamin Morris’ article on FiveThirtyEight.com related to Seattle’s final offensive play in Super Bowl XLIX.

Videos

1. Video of the presentation can be found here:

https://www.youtube.com/watch?v=ZZl8r_K7I5E&feature=youtu.be

Objectives

We initially attempted to recreate a primary result from the article, in which the probabilities of sequential play outcomes and overall game outcomes are computed, and in which those estimates change based on some additional assumptions. While the objective of recreating the model is important objective, we felt it was unrealistic to reach that point without having more information on the data Morris’ used and in how the model was actually computed. Our attention instead turned to numerically replicating some elements of the model, such as the probability of scoring a touchdown on a run play, and to evaluating whether tweaks to the model were reasonable.

Situation

1. We start with the play. This image from NFL Breakdowns shows Seattle in a shotgun formation at New England’s 1-yard line in the seconds just prior to the snap. Trailing by four points, a touchdown would have put Seattle up by three (assuming they go for and get the PAT), something many an observer would have as much assumed was going to happen. Russell Wilson’s attempted pass on a slant route to Ricardo Lockette.”

1. points: Touchdown = 6 pts; Field Goal = 3 puts; Point After Touchdown (easy kick) = 1 pt
2. attacking team (offense) scores a touchdown by getting the ball into the end zone (area beyond goal line)
3. offense has four attempts to move the ball 10 yds; if inside 10 yard line, then just the number of attempts to goal
4. ball is advanced by throwing the ball to someone who catches it or by someone running with the ball (i.e., pass or run the ball)
5. a given play ends with the person with the ball is tackled or goes out of bounds or when its passed and not caught

In a simpler view, imagine having two bowls each with three colored balls.  You pull a ball out blindfolded one at a time.  Pull a red ball you win, a black ball you lose, and a yellow ball lets you pull again.  However if you pull three yellow balls in a row you also lose.  There are two bowls to choose from, one called run and one called pass, each has a different amount amount of red, yellow, and black balls.

Using this mentality we created a probability tree that includes all possibilities from this decision.

Implementation

# 45k observations by 45 vars