(clock ticking)
- [Narrator] 0.4 seconds.
That's the time it takes you to blink.
It's also about how long goalkeepers have
to save a penalty kick
or fail trying.
And it's certainly not enough time
for a goalie to react and respond.
So goalies can't solely rely on their speed and agility
to save a penalty kick.
Instead they have to pretty much guess
which direction to go and rely on either luck
or game theory.
(playful music)
Game theory is a popular strategy in economics
where the outcome of a situation relies more
on how well you predict your opponent's actions
than how you perform your own.
So since the goalie has no choice but to guess,
they're better off guessing logically than randomly.
That's where economists come in.
- [Ignacio] I would like to know what you do in the last
80 penalty kicks you faced?
Do you have any tendencies?
What does this guy do against right-footed kickers
versus left-footed kickers?
- [Narrator] That's economist Ignacio Palacios-Huerta.
He studied over 11,000 penalty kicks,
and in 2008 during the UEFA Champions League Final,
it paid off, sort of.
It was Manchester United against Chelsea.
The game came down to a penalty shootout
which was the perfect opportunity for Chelsea
to put Huerta's advice into action.
Along with several pointers Huerta
had given Chelsea's goalie
a key insight about Manchester United
star Cristiano Ronaldo.
Ronaldo would almost certainly kick the ball to the right
if he paused on the run-up.
And the advice worked.
Ronaldo indeed paused and indeed kicked the ball
to the right.
Chelsea's goalie followed Huerta's advice
and made the save.
Ultimately Manchester United won the game,
but despite Chelsea's loss,
it was clear that economists and statisticians
can help even the odds when it comes to penalty kicks.
Because otherwise, it's a crap shoot for the goalie.
In 2014 for example,
FiveThirtyEight calculated that 72.5% of penalties
in World Cup history went in.
For all competitions worldwide,
it's even higher.
And when you take a closer look,
it's no wonder.
Human response time takes roughly 1/10 of a second
to kick in.
The average kicker kicks a 70 mile per hour ball,
which means the goalie won't even register
the ball's direction until it's about 25 feet away.
It will take him another .5 to .7 seconds
to react and reach for the ball,
but by that point,
it's all over.
Now the goalie can improve the odds
if they start to move before the ball is even kicked,
but the goalie still has to basically guess a side
and just go for it.
So if time is the goalie's enemy,
maybe we should just move the penalty kicker further back.
But for now, economists are a goalie's best friend
when it comes to stopping penalty kicks,
and turns out, Huerta is helping a team
in the 2018 World Cup,
though he wouldn't tell us who.
(playful music)