Week 3, Lions at Packers
4th-and-2, 8:26 remaining in 3rd quarter, Down by 21
The Lions went for it on a 4th-and-2 on the Packers’ 2. The NYT 4th Down bot was thinking the same thing, although attempting a field goal would have been fine, too.
If you disagree

I lean slightly towards going for it, but I don’t have strong feelings here – my numbers tell me that either going for it or attempting a field goal could be the best play. Specifically, attempting a field goal would be the right call if you think the Lions’ chances of converting on fourth down are less than 21 percent. (Based on my analysis, I’d give the Lions a 46 percent chance to get a first down here.)

Here's the full breakdown of my calculations:

Option Chance of converting
Chance of winning
Before play
After play Change
Go for it4th and 2, opp. 2 46% 2% 2% -
Field goal try19 yard kick (est.) 98% 2% 2% -
Punt 2% 1% –1%
What coaches usually do
Go for it 51% of the time
Field goal try 49% of the time
Punt -
Based on about 1,045 fourth downs in similar situations since 2001.
What happened

Matthew Stafford pass to the right to Anquan Boldin for 2 yards for a TOUCHDOWN. Matthew Stafford pass to the right to Anquan Boldin for 2 yards for a TOUCHDOWN.

Where did these numbers come from?

To estimate a team’s chances of winning, I use a mathematical model that accounts for a whole lot of variables — including the difference in score, the time remaining in the game, and the number of timeouts each team has left. On top of that, I have models for the likelihood that a team makes a field goal and the likelihood that it will convert a first down.

By combining all of this information, I can come up with the best decision a team can make, according to math.

If you want even more details about the numbers behind my decisions, my full model is available on GitHub. Help make me better!