And the fourth aspect is that you have also to devise some interactive feature to allow the user to explore her dataset in easy and useful ways, because, as we have seen in the first lecture, it is essential for the user to be able to interact with her data to become more engaged with the data, and when the user is more engaged with data it is easier to discover interesting patterns and to discover for example cause-effect relations, if he changes something on some data and she sees that another part of the visualization changes, he might infer a cause-effect relation.