Static vs. dynamic time mapping in radial composite indicator visualization

Composite Indicators (CIs), are a common measurement and benchmarking tool that are used to reflect and measure multidimensional concepts such as digital divides, individual's wellbeing and more. Measurement iterations produce a series of timeoriented data, which stakeholders as well as the general public might be interested to interpret. Visualization of a CI is highly recommended in order to ease interpretation, and many CI websites use radial solutions to visualize CIs. Yet it is unclear how to visualize the temporal dynamics in radial diagrams. Static solutions, mapping time to small multiples might be challenging due to screen space issues. Dynamic solutions are appealing, yet, there is no clear empirical evidence on benefits of dynamic time coding in radial diagrams. In this paper, we compare static vs. dynamic time mapping using two radial CI visualization methods. The popular Radar chart technique is compared to the innovative Flower chart as used in the well-known OECD Better Life index. We compare users' performance and preferences empirically under formal task taxonomy, adjusted to CI tasks. Results indicate that in general, static time encoding was more effective than dynamic encoding. Still, an in depth analysis showed that the dynamic approach is a feasible and sometimes even better solution for important CIs tasks, leveraged by the fact that users seem to like and enjoy it.