The Trends in Adult BMI is an interactive visualization which show the changes in BMI (body-mass index) in 200 countries for the past four decades.
The visualization conveys its meaning effectively by using appropriate marks and channels. The X-axis is the timeline, from 1974-2014. The Y-axis is the percentage of population, from 0-100%. It uses only one marks and two channels, with the area as mark and the color/hue as channels. All population were categorized into 7 different levels of obesity, with the deep red as highest BMI level and deep blue as the lowest.
The visualization has two filters, one is filtering by gender and another is filtering the order of countries by different ways, such as obesity or underweight. Since the main audience of this visualization shall be some one like researcher, it will be better it could provide more ways of interaction which allows user do some further discovering. For example, a practical filter is filtering the data by people’s age. It could also filter the data by countries or continents.
Reference:
https://public.tableau.com/en-us/s/gallery/four-decades-prevalence-adult-bmi