Categorical or Topical Data Visualizations
Comparisons
Comparisons are an important aspect of social studies education. The Michigan K-12 Social Studies Standards ask students to compare physical, cultural, political, and economic aspects beginning in early elementary and in every grade level thereafter. Bar graphs, line graphs, pie charts, population pyramids, and treemaps are commonly used to compare categories of data. In his data documentary, The Fallen of World War II, Neil Halloran makes extensive and effective use of bar graphs to compare countries' losses in WWII, and to compare total WWII deaths to deaths in other wars.
Distribution
Bubble charts, multi-set bar graphs, and scatterplots help us to see distributions of data. That is, they help us see how data is spread out or grouped. In social studies, we are often concerned about outliers -- people or countries who lie outside of the majority with regard to income, education, access to resources and so on. For example the Our World in Data visualization to the left, which displays countries by a combination of their literacy rates and numeracy rates (the size of the circle corresponds to population) raises questions about what is going on in countries at the lower left of the graph.
Patterns
Area graphs, bar graphs, bubble charts, line graphs, population pyramids, and scatterplots all reveal patterns that give meaning to the data and allow us to draw inferences. Look, for example at the population pyramid for Germany on the left. Being able conclusions from the population pyramid depends upon observation of patterns -- in this case, observing that a large portion of the population is "middle-aged" tells you that birth rates, and therefore population growth, are low. On the other hand, the population pyramid for Nigeria on the right shows that there are a lot of young people and very few people past the typical window of child-rearing. This points toward a high birth rate and fast population growth.
Proportions
Sometimes in social studies, we are interested in questions related to proportions or parts of a whole. For example, what proportion of the world's nuclear weapons are concentrated in non-democratic nations? What fraction of global deaths each year are due to violent conflict? To curable diseases? In cases like these, data visualizations like bubble charts, pie charts, stacked bar graphs, treemaps, and word clouds are useful. The treemap above, for example, displays different categories for causes of childhood deaths, and shows the proportions for specific causes within the different categories in 1990. It then overlays information about proportionate causes of death in 2017 so that observers can see what's changed.
Relationships
Bubble charts and scatterplots are ideal for showing relationships between variables. This is what Hans Rosling depends upon in the compelling arguments he made in his many TED Talks. Though he depends on "low-tech" visualization for a large portion of this video, he drives home his point toward the end by highlighting the relationship between child mortality and children per women. He argues that in order to slow the pace of population growth in the world, we need to provide better access to resources and healthcare in the poorest countries so that children are more likely to survive and thrive and family sizes decrease.
