<story><title>U.S. life expectancy varies by more than 20 years from county to county</title><url>https://www.washingtonpost.com/news/to-your-health/wp/2017/05/08/u-s-life-expectancy-varies-by-more-than-20-years-from-county-to-county/?hpid=hp_hp-top-table-main_life-expectancy-11am%3Ahomepage%2Fstory</url></story><parent_chain><item><author>generj</author><text>One possible partial explanation for this is the same reason why the Bill Gates Foundation wasted a bunch of money fostering small high schools. Smaller high schools were some of the best performing schools...but also some of the worst [0].&lt;p&gt;The answer is just that small counties have high variance. By chance some small counties will be a lot higher or lower than the national average.&lt;p&gt;I would be interested in seeing a Cox Proportional Hazards Model would show if the remaining changes are related to pollution, meth, economics, etc.&lt;p&gt;[0]&lt;a href=&quot;http:&amp;#x2F;&amp;#x2F;marginalrevolution.com&amp;#x2F;marginalrevolution&amp;#x2F;2010&amp;#x2F;09&amp;#x2F;the-small-schools-myth.html&quot; rel=&quot;nofollow&quot;&gt;http:&amp;#x2F;&amp;#x2F;marginalrevolution.com&amp;#x2F;marginalrevolution&amp;#x2F;2010&amp;#x2F;09&amp;#x2F;the...&lt;/a&gt;</text></item></parent_chain><comment><author>Nacraile</author><text>Sample-size-based variance is a nice nit to pick, but it doesn&amp;#x27;t really seem to match the data presented in the article.  Outcomes are strongly correlated in adjacent counties across the map, which is not predicted by sample-size (which would produce uncorrelated noise, in inverse proportion to population density).  On the other hand, there is substantial correlation between the given geographic distribution of life expectancy changes and geographic distribution of wealth, as observed in the article.</text></comment>
<story><title>U.S. life expectancy varies by more than 20 years from county to county</title><url>https://www.washingtonpost.com/news/to-your-health/wp/2017/05/08/u-s-life-expectancy-varies-by-more-than-20-years-from-county-to-county/?hpid=hp_hp-top-table-main_life-expectancy-11am%3Ahomepage%2Fstory</url></story><parent_chain><item><author>generj</author><text>One possible partial explanation for this is the same reason why the Bill Gates Foundation wasted a bunch of money fostering small high schools. Smaller high schools were some of the best performing schools...but also some of the worst [0].&lt;p&gt;The answer is just that small counties have high variance. By chance some small counties will be a lot higher or lower than the national average.&lt;p&gt;I would be interested in seeing a Cox Proportional Hazards Model would show if the remaining changes are related to pollution, meth, economics, etc.&lt;p&gt;[0]&lt;a href=&quot;http:&amp;#x2F;&amp;#x2F;marginalrevolution.com&amp;#x2F;marginalrevolution&amp;#x2F;2010&amp;#x2F;09&amp;#x2F;the-small-schools-myth.html&quot; rel=&quot;nofollow&quot;&gt;http:&amp;#x2F;&amp;#x2F;marginalrevolution.com&amp;#x2F;marginalrevolution&amp;#x2F;2010&amp;#x2F;09&amp;#x2F;the...&lt;/a&gt;</text></item></parent_chain><comment><author>flexie</author><text>But even the small counties have populations in the several hundreds or thousands, right? Outliers that die at 33 or 103 affect the average little when you have a population of 2,000.</text></comment>