# Politics

126 postsAsk the experts to name the success metric of good data visualization, and you will receive a dozen answers. The field doesn't have an all-encompassing metric. A useful reference is Andrew Gelman and Antony Urwin (2012) in which they discussed the tradeoff between beautiful and informative, which derives from the familiar tension between art and science. For a while now, I've been intrigued by metrics that measure "effort". Some years...

This is the final post on the series of data visualization deployed by FiveThirtyEight to explain their election forecasting model. The previous posts are here, here and here. I'm saving the best for last. This snake-pit chart brings me great joy - I wish I came up with it! This chart wins by focusing on a limited set of questions, and doing so excellently. As with many election observers, we...

Continuing our review of FiveThirtyEight's election forecasting model visualization (link), I now look at their headline data visualization. (The previous posts in this series are here, and here.) It's a set of 22 maps, each showing one election scenario, with one candidate winning. What chart form is this? Small multiples may come to mind. A small-multiples chart is a grid in which every component graphic has the same form -...

In yesterday's post, I reviewed one section of 538's visualization of its election forecasting model, specifically, the post focuses on the probability plot visualization. The visualization, technically called a pdf, is a mainstay of statistical graphics. While every one of 40,000 scenarios shows up on this chart, it doesn't offer a direct answer to our topline question. What is Nate's call at this point in time? Elsewhere in their post,...

As anyone who is familiar with Nate Silver's forecasting of U.S. presidential elections knows, he runs a simulation that explores the space of possible scenarios. The polls that provide a baseline forecast make certain assumptions, such as who's a likely voter. Nate's model unshackles these assumptions from the polling data, exploring how the outcomes vary as these assumptions shift. In the most recent simulation, his computer explores 40,000 scenarios, each...

An anonymous reader submitted this mirrored bar chart about violent acts by extremists in the 16 German states. At first glance, this looks like a standard design. On a second look, you might notice what the reader discovered- the chart used two different scales, one for each side. The left side (red) depicting left-wing extremism is artificially compressed relative to the right side (blue). Not sure if this reflects the...

You have two numbers +84% and -25%. The textbook method to visualize this pair is to plot two bars. One bar in the positive direction, the other in the negative direction. The chart is clear (more on the analysis later). But some find this graphic ugly. They donâ€™t like straight lines, right angles and such. They prefer circles, and bends. Like PBS, who put out the following graphic that was...

Over the weekend, Georgia's State Health Department agitated a lot of people when it published the following chart: (This might have appeared a week ago as the last date on the chart is May 9 and the title refers to "past 15 days".) They could have avoided the embarrassment if they had read my article at DataJournalism.com (link). In that article, I lay out a set of the "unspoken conventions,"...

Reader Lucia G. sent me this chart, from Ars Technica's FAQ about the coronavirus: She notices something wrong with the axis. The designer took the advice not to make a dual axis, but didn't realize that the two metrics are not measured on the same scale even though both are expressed as percentages. The blue bars, labeled "cases", is a distribution of cases by age group. The sum of the...

Twitter people are talking about this chart, from NPR (link): This was published on Wednesday after Super Tuesday, the day on which multiple states held their primary elections. On the Democratic side, something like a third of the delegates were up for grabs (although as the data below this chart shows, a big chunk of the delegates, mostly from California and Texas, have yet to be assigned to a candidate...