Observational versus Experimental

• The example about drug testing and drug use is

• A. Observational• B. Experimental• C. Logical• D. Case study

What happens when an association is not perfect?

• A. it is not causal• B. the cases were not randomly selected• C. there could still be a causal effect• D. we have proven causation

Cause & Effect: Cell Phones and NFL Football

CURRENT DEBATEQ: Do cell phones cause cancer?

Cause and Effect

• Cause (X): Cell Phone “use” Frequency, Proximity, Models, Towers

• Effects (Y): Degraded HealthCancer Brain, Skin, Other OrgansHearing Loss

How would we study the relationship?

• How would we study the relationship? What do we need to do?

• How would we convince ourselves that our research was believable?

• How would we convince others to believe our research?

The Evidence

Should we worry?

The Contrary Evidence

Does Evidence Matter?

Let’s merge problems…

Public Policy

• Create new phones• Locate towers• Prevent certain types of uses• Prevent certain types of users (Children,

Pregnant women)• Education to change behaviors• Consider the opportunity costs• Do nothing. (Don’t worry about it.)

Q: Does NFL Football Reduce Crime?

The Controversy

Ray Lewis Speaks Out

Ray Lewis as told to ESPN’s Sal Paolantonio:

“Do this research if we don’t have a season — watch how much evil, which we call crime, watch how much crime picks up, if you take away our game,”The NFL lockout affects “way more than us” — the owners and the players.“There’s too many people that live through us, people live through us.” “Yeah, walk in the streets, the way I walk the streets, and I’m not talking about the people you see all the time.”

When asked why he thought crime would increase if the NFL doesn’t play games this year, Lewis said: “There’s nothing else to do, Sal.”

Cause & Effect

• Cause (X): NFL Football

• Effect (Y): Crime Rate

• Hypothesis: NFL Football reduces Crime.

Ravens RB Ray Rice comes to Lewis’ defense:

“Any time Ray [Lewis] speaks about something, it comes from his heart. He hit on a point where people are really struggling. It doesn’t necessarily have to be us that are struggling because we might make a few more dollars than other people. But what about the people that work in the concession stands? What about the people that work at the facility that had to take pay cuts? What about the people that got laid off?”

An Alternative Perspective on The Causes of Crime

A more complex explanation

• Poverty leads to crime…• BUT NFL football impacts employment and

hence keeps some people from falling into poverty

• OR NFL football as entertainment mitigates the effects of poverty on crime by deflecting attention from an impoverished existence

The Evidence Supporting the Lewis Hypothesis

What type of evidence do we need? • Variation in NFL activity– Temporal (Season versus off-season)– Locational (Does it matter if you have a home city

or home state team?)• Crime rates– National, State, Local– Types of crime

The Evidence Supporting the Lewis Hypothesis

What type of evidence do we need? • Controls– State of the economy (unemployment, poverty)– Weather– Interest in football

• Problems– Multicollinearity

The Contrary Evidence

Superbowl Sunday is often one of the highest crime rate days of the year as angry husbands and boyfriends wreak domestic violence on their supposed “loved ones”.

NFL Off Season

Perhaps employing these individuals as football players reduces crime. In that case, a

lockout or strike would increase crime.

Hypotheses about politics?

• Return to Downs, Economic Theory of Democracy.

• Your hypotheses. What questions do you have about the political world? How would we study them?