  Comprehending and exploring large and complex data is becoming increasingly
important for users in a wide range of application domains. Still, non-experts
in visual data analysis often have problems with correctly reading and
interpreting information from visualizations 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 3 studies:
1) Firstly, we explored the effect of vis onboarding, using an interactive
step-by-step guide, on user performance for four increasingly complex
visualization techniques. 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. Furthermore, participants commented that for highly familiar
visualization types no onboarding is needed. 2) Second, we performed another
study with MTurk workers to assess if there is a difference in user
performances on different 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 sentiment analysis, followed
by the scrollytelling tutorial and the interactive step-by-step guide. 3) For
our third study with students, we gathered data on users' experience in using
an in-situ scrollytelling for the VA tool. The results showed that they
preferred scrollytelling over the tutorial integrated into the landing page. In
summary, the in-situ scrollytelling approach works well for visualization
onboarding and a video tutorial can help to introduce interaction techniques.
