Comparative evaluations of visualization onboarding methods

Comprehending and exploring large and complex data is becoming increasingly important for a diverse population of users in a wide range of application domains.Visualization has proven to be well-suited in supporting this endeavor by tapping into the power of human visual perception.However,non-experts in the field of visual data analysis often have problems with correctly reading and interpreting information from visualization idioms that are new to them.To support novices in learning how to use new digital technologies,the concept of onboarding has been successfully applied in other fields and first approaches also exist in the visualization domain.However,empirical evidence on the effectiveness of such approaches is scarce.Therefore,we conducted three studies with Amazon Mechanical Turk(MTurk)workers and students investigating visualization onboarding at different levels:(1)Firstly,we explored the effect of visualization onboarding,using an interactive step-by-step guide,on user performance for four increasingly complex visualization techniques with time-oriented data:a bar chart,a horizon graph,a change matrix,and a parallel coordinates plot.We performed a between-subject experiment with 596 participants in total.The results showed that there are no significant differences between the answer correctness of the questions with and without onboarding.Particularly,participants commented that for highly familiar visualization types no onboarding is needed.However,for the most unfamiliar visualization type—the parallel coordinates plot—performance improvement can be observed with onboarding.(2)Thus,we performed a second study with MTurk workers and the parallel coordinates plot to assess if there is a difference in user performances on different visualization onboarding types:step-by-step,scrollytelling tutorial,and video tutorial.The study revealed that the video tutorial was ranked as the most positive on average,based on a sentiment analysis,followed by the scrollytelling tutorial and the interactive step-by-step guide.(3)As videos are a traditional method to support users,we decided to use the scrollytelling approach as a less prevalent way and explore it in more detail.Therefore,for our third study,we gathered data towards users’experience in using the in-situ scrollytelling for the VA tool Netflower.The results of the evaluation with students showed that they preferred scrollytelling over the tutorial integrated in the Netflower landing page.Moreover,for all three studies we explored the effect of task difficulty.In summary,the in-situ scrollytelling approach works well for integrating onboarding in a visualization tool.Additionally,a video tutorial can help to introduce interaction techniques of visualization.