How have wealth and health evolved across 142 nations from 1952 to 2007?
This visualization explores the relationship between national wealth (GDP per capita) and human wellbeing (life expectancy) across 142 countries from 1952 to 2007. The central question is: Have poorer nations caught up with wealthier ones in health outcomes over 55 years? Secondary questions include: How do world regions compare over time? Which individual countries show the most dramatic trajectories?
A bubble chart (inspired by Hans Rosling's Gapminder) maps three quantitative variables simultaneously — GDP (x-axis, log scale), life expectancy (y-axis), and population (bubble area). A logarithmic x-axis is used because GDP per capita spans several orders of magnitude; a linear scale would compress all low-income countries into an unreadable band. Continent membership is encoded with a distinct color palette.
Interaction rationale: A year slider with play/pause animation makes temporal trends vivid — this is the most impactful "aha" moment when watching countries move right and upward over time. Continent buttons allow regional isolation. Country search highlights individual trajectories. Hover tooltips provide precise values on demand. Zoom and pan support exploration of dense low-income clusters. Clicking a bubble also highlights/pins that country.
Alternatives considered: A choropleth map was rejected because temporal comparison is harder. A connected scatterplot was considered for tracking single countries but loses the distributional view. D3.js was chosen over Vega-Lite for greater interaction customizability.
Total development time: approximately 14 hours. The most time-consuming parts were (1) coordinating the zoom transform with animated bubble transitions so both work simultaneously, and (2) ensuring the continent filter, country search, and year slider interact correctly together without conflicts. GitHub Pages deployment was straightforward and took under 20 minutes.