The Hierarchical Task Analysis(HTA) was part of the user research process. It was mainly designed focusing on the primary knowledge about the existing systems and activities.

In this graphical representation of task analysis, the starting point consists of the user goal. It consists of,  to remember to take the medicine and access the medicines from the dosette box. Further, it consists of all the tasks performed by the user to achieve the main goal and then into sub-tasks and so on.

It provided a good understanding of the interaction and at whichever level of abstraction it is appropriate.