Exploring Project Tycho - Treemaps and Correct Hierarchies

Hello,
I am a student studying computer science at Swansea University, we are working on an assignment that involves exploring data from Project Tycho (https://www.tycho.pitt.edu/) and applying various analytical tools and techniques in order to make various observations. Here is a treemap that I have created in Tableau, representing information on meningitis and meningococcal meningitis within 10 US States, more details can be found below:

Visual Design Type: Treemap.

Name of Tool: Tableau

Country: U.S.

Disease: Meningitis and Meningococcal Meningitis

Year: 1905-1964

Visual Mappings:

– filter: the top 10 states with the highest number of records for both types of meningitis were filtered out for use.

– Colour: colour is mapped to the difference between the number of fatalities among the different states.

– Shape: each bottom level rectangle represents a state.

– Size: the size of each bottom-level rectangle is mapped to the number of records for each respective condition for a given state, while the size of each higher-level rectangle represents the number of records for each condition.

– Position: the position of each rectangle/state is determined by decreasing frequency in the number of records, the more records a state holds, the further it is to the left.

– Hierarchy: the states are grouped by disease → state

Unique Observation: We can easily compare rates of both diseases and fatalities within states, i.e., We can see that Wisconsin has a lower rate of fatalities for both diseases comparatively to other states. We can also see that for its rate of Meningococcal Meningitis Texas has a relatively low rate of Meningitis, whereas other states tend to place at similar positions within each condition.

Data Preparation: In order to create the hierarchy, the datasets for Meningitis and Meningococcal Meningitis within the US were combined.

DOIs:
Meningitis: 10.25337/T7/ptycho.v2.0/US.7180009
Meningococcal Meningitis: 10.25337/T7/ptycho.v2.0/US.192644005

So here I have a couple of questions, if anyone would like to help out it would be greatly appreciated!

  1. Does my treemaps hierarchy make sense and is there any better technique available to explore this data?
  2. Does my explanation of the mapping make sense? Is there any information I seem to have left out?

Thank you very much for your time!

Reference:
Kong, N., Heer, J., and Agrawala, M. Perceptual
guidelines for creating rectangular treemaps.
Visualization and Computer Graphics, IEEE
Transactions on 16, 6 (2010), 990–998.
(https://idl.cs.washington.edu/files/2010-Treemaps-InfoVis.pdf)

Hi,
To answer your questions:

  1. Yes I do believe that your hierarchy makes sense, since you are looking at just the U.S, maybe another visualisation you could use is a symbol map. It would show the geographic locations of the cases and fatalities of each disease. (Technique is on Tableau)

  2. Your mappings do make sense, especially explaining the bottom-level and higher-level rectangles. There is no information that you have left out.

Matt