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Summary of Week 3

This week, we looked at the effect of police on crime. The rational choice model predicts that having more police officers should reduce crime by increasing the probability of punishment, …

Punishment severity and crime

Consider the following examples of real-life “get-tough-sentencing” policy reforms: 1) imposing jail terms for reckless driving instead of fines 2) imposing an automatic prison sentence for a major parole violation …

Why does more police reduce crime, again?

So far, we talked about the importance of obtaining regression results that have both causal interpretation and clear policy implication. Existing research evidence strongly suggests that police matters. When the …

Surveillance cameras and crime prevention

Under the rational choice model of crime, police reduces crime by increasing the expected probabilities of arrest and punishment. But having a larger police force is not the only way …

Difference-in-differences analysis

When we want to investigate the causal effect of the increased police presence on crime rates, it is usually more preferable to compare the changes in crime rates and police …

Validity issues

In our previous step, we encountered several examples of good identifying variations that enabled researchers to recover the causal effects of police on crime. The examples included highly unusual events …

Elasticity

Whether bigger police budget and more police officers cause crime to fall has been our main research question so far, but just as important is by how much crime falls. …

Summary of Week 2

The historic crime rise during the 1980s and an equally drastic crime decrease in the 1990s challenged and motivated many economists to look for explanations. We saw the set of …

Panel data and fixed effect regression

Looking at a within-unit comparison instead of an across-unit comparison may be a better way to study a causal relationship of interest. For example, if we compare the size of …

Regression analysis exercise (Optional)

[Note: The exercise presented in this step requires Microsoft Excel. If you already know how to run linear regression using a different computer program, you can just skim through the …

Multiple regression

If the positive relationship between larceny and inequality is in fact driven by another factor that is correlated with both larceny and inequality (e.g., the share of youth population), including …

Multiple regression exercise (Optional)

[Note: Again, the exercise presented in this step requires Microsoft Excel. If you already know how to run linear regression using a different computer program, you can just skim through …