# Articles by d sparks

### Mapping Public Opinion: A Tutorial

July 18, 2012 |

At the upcoming 2012 summer meeting of the Society of Political Methodology, I will be presenting a poster on Isarithmic Maps of Public Opinion. Since last posting on the topic, I have made major improvements to the code and robustness of the modeling approach, and written a tutorial that illustrates the ... [Read more...]

### Isarithmic Maps of Public Opinion Data

October 24, 2011 |

As a follow-up to my isarithmic maps of county electoral data, I have attempted to experiment with extending the technique in two ways. First, where the electoral maps are based on data aggregated to the county level, I have sought to generalize the method to accept individual responses for which ... [Read more...]

### Choropleth tutorial and regression coefficient plots

February 21, 2011 |

About two weeks ago, I gave short talk at Duke, wherein I presented a brief tutorial on creating choropleth maps in R using ggplot2. Since the code is already written, and the data and shapefiles already hosted online, I thought I would share the tutorial more widely. A .ZIP file ... [Read more...]

### Electoral Marimekko Plots

December 6, 2010 |

To be reductive, visual displays of quantitative information might be reasonably categorized on a continuum between “data display” and “statistical graphics.” By statistical graphics, I mean a plot that displays some summary of or relationship amongst several variables, likely having undergone some processing or analysis. This may be as simple ... [Read more...]

### Isarithmic History of the Two-Party Vote

November 15, 2010 |

A few weeks ago, I shared a series of choropleth maps of U.S. presidential election returns, illustrating the relative support for Democratic, Republican, and third Party candidates since 1920. The granularity of these county level results led me to wonder whether it would be possible to develop an isarithmic map ... [Read more...]

### Choropleth Maps of Presidential Voting

November 1, 2010 |

Having always appreciated the red and blue cartograms and cartographs of geographic electoral preferences, such as those made available by Mark Newman, I sought to produce similar maps, but include information about support for non-“state-sponsored” parties, and to extend the coverage back in time. I was able to find ... [Read more...]

### K-Means Redistricting

October 18, 2010 |

U.S. Congressional districts are today drawn with the aim of maximizing the electoral advantage of the state’s majority party, subject to some constraints, including compactness (which can be measured in numerous ways) and a “one person, one vote” standard. What if, instead of minimizing population variance across districts, ... [Read more...]