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Week5-Geographical Analysis with Tableau: Creating and Utilizing Buffer Areas

This post was originally published on The Data School blog between 2018 and July 2025, before our program was renamed to MIP’s Analytics Career Accelerator. References throughout this article to “The Data School” or “DS” all refer to what is now MIP’s Analytics Career Accelerator. The program, its people, and its commitment to launching outstanding analytics careers remain the same – just under a new name.

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In Tableau, one commonly utilized graphic is the map, which can be used to analyze conditions specific to various areas. Let’s explore how we can leverage Tableau to achieve this effect:

So, how can we identify all the counties situated within a certain number of miles from a chosen county? In this case, we would utilize a map that not only pinpoints the locations of the selected counties but also outlines the state boundaries of the relevant states.

Step1: Create two maps

To simultaneously display the selected counties and state boundaries, we could distinguish between counties and states before merging them using a dual axis. Also, it’s important to note that the term ‘total beds’ encompasses the sum of staffed beds and Intensive Care Unit (ICU) beds.

Step2: Create Parameters

As per the requirements, we need to facilitate users to select the county of their interest and define the radius (in miles) of the area they wish to view. To accomplish this task, we can use a familiar tool — the parameter.

Step 3: Create a buffer area in Tableau

In Tableau, creating a buffer area typically involves the following sequential steps:

  • Making Points: The makepoint() function in Tableau is used to create a point on the map, using latitude and longitude coordinates. This point is where the buffer area will be centered.
  • Calculating Distance: After making the points, you calculate the distance between these points. The distance() function can be used to determine the distance between two geographical points, which is crucial for defining the radius of the buffer area.
  • Creating Buffer Area

The final step involves adding the buffer to a filter. This action will help to clearly distinguish between areas that fall within the buffer (i.e., within the specified distance from the chosen point) and those that are outside of it.

 

 

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