This example visualizes average BMI across US regions, split by smoker status, using a faceted bar chart. The chart shows that the southeast region has the highest BMI, while smokers do not necessarily have higher BMIs than nonsmokers. The visualization is built with Vega-Lite API and D3, reading data from a CSV file. It uses aggregated bar marks, with region as columns, smoker status on the x-axis, and average BMI on the y-axis, with tooltips for detailed values.