doc/AER/Guns.html

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<table style="width: 100%;"><tr><td>Guns</td><td style="text-align: right;">R Documentation</td></tr></table>

<h2>More Guns, Less Crime?</h2>

<h3>Description</h3>

<p>Guns is a balanced panel of data on 50 US states, plus the District of Columbia (for a
total of 51 states), by year for 1977&ndash;1999.
</p>


<h3>Usage</h3>

<pre><code class='language-R'>data("Guns")</code></pre>


<h3>Format</h3>

<p>A data frame containing 1,173 observations on 13 variables.
</p>

<dl>
<dt>state</dt><dd><p>factor indicating state.</p>
</dd>
<dt>year</dt><dd><p>factor indicating year.</p>
</dd>
<dt>violent</dt><dd><p>violent crime rate (incidents per 100,000 members of the population).</p>
</dd>
<dt>murder</dt><dd><p>murder rate (incidents per 100,000).</p>
</dd>
<dt>robbery</dt><dd><p>robbery rate (incidents per 100,000).</p>
</dd>
<dt>prisoners</dt><dd><p>incarceration rate in the state in the previous year
(sentenced prisoners per 100,000 residents; value for the previous year).</p>
</dd>
<dt>afam</dt><dd><p>percent of state population that is African-American, ages 10 to 64.</p>
</dd>
<dt>cauc</dt><dd><p>percent of state population that is Caucasian, ages 10 to 64.</p>
</dd>
<dt>male</dt><dd><p>percent of state population that is male, ages 10 to 29.</p>
</dd>
<dt>population</dt><dd><p>state population, in millions of people.</p>
</dd>
<dt>income</dt><dd><p>real per capita personal income in the state (US dollars).</p>
</dd>
<dt>density</dt><dd><p>population per square mile of land area, divided by 1,000.</p>
</dd>
<dt>law</dt><dd><p>factor. Does the state have a shall carry law in effect in that year?</p>
</dd>
</dl>


<h3>Details</h3>

<p>Each observation is a given state in a given year. 
There are a total of 51 states times 23 years = 1,173 observations.
</p>


<h3>Source</h3>

<p>Online complements to Stock and Watson (2007). 
</p>


<h3>References</h3>

<p>Ayres, I., and Donohue, J.J. (2003). Shooting Down the &lsquo;More Guns Less Crime&rsquo; Hypothesis.
<em>Stanford Law Review</em>, <b>55</b>, 1193&ndash;1312.
</p>
<p>Stock, J.H. and Watson, M.W. (2007). <em>Introduction to Econometrics</em>, 2nd ed. Boston: Addison Wesley.
</p>


<h3>See Also</h3>

<p><code>StockWatson2007</code></p>


<h3>Examples</h3>

<pre><code class='language-R'>
## data
data("Guns")

## visualization
library("lattice")
xyplot(log(violent) ~ as.numeric(as.character(year)) | state, data = Guns, type = "l")

## Stock &amp; Watson (2007), Empirical Exercise 10.1, pp. 376--377
fm1 &lt;- lm(log(violent) ~ law, data = Guns)
coeftest(fm1, vcov = sandwich)

fm2 &lt;- lm(log(violent) ~ law + prisoners + density + income + 
  population + afam + cauc + male, data = Guns)
coeftest(fm2, vcov = sandwich)

fm3 &lt;- lm(log(violent) ~ law + prisoners + density + income + 
  population + afam + cauc + male + state, data = Guns)
printCoefmat(coeftest(fm3, vcov = sandwich)[1:9,])
            
fm4 &lt;- lm(log(violent) ~ law + prisoners + density + income + 
  population + afam + cauc + male + state + year, data = Guns)
printCoefmat(coeftest(fm4, vcov = sandwich)[1:9,])
</code></pre>


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