Visual Poisson Distribution Calculator

Poisson distribution is so important that I had to learn it in a recent project. Learnt to use it to be exact.

Thus came an idea to visualize it in Tableau, because I couldn't find a good visual reference on the web about it.

Here you go. It shows two charts:
1.Probability distribution per K (the number of occurrences).
2.Cumulative probability for all events where the number of occurrences <=K.
3.Both λ and the range of K are in parameters.

Click image to view the interactive version.

You might notice that we need to calculate the factorials of K in Poisson distribution. The initial calculation formula failed because the numbers were too big for integer operations. A workaround is found using floating point calculations.

[Update]Added an alternative view that highlights the complementary property of <=K and >K probabilities:

Click image to view the interactive version.

(Refresh the page if you want to view the gif image multiple times. Or go to Tableau Public and click the button at the top-right corner.)

Jake and I collaborated on a dashboard. He told me that he learnt a way to create an in-place help page in Tableau. He first saw it at a conference somewhere and couldn't recall who the speaker was. So I am blogging here about it but the credit goes to somebody else. If anyone knows who the original creator is, leave a comment below.

The key idea is to float a semi transparent worksheet on top of the dashboard, where a help text box is strategically placed on top of each chart. This way, we can explain how to view each chart and what data points are important, etc. This worksheet is collapsible by a show/hide button.

Below I would like to show how this worksheet can be constructed.

1. Sheet with a single data mark.

Double click the empty space in Marks panel and add two single quotes. Make the null pill a text label. This creates a single null mark.
Set the view as "Entire View"

2. Create an show/hide button

Go to the target dashboard
Drag a floating vertical container to the dashboard, making it cover all the area of interest.
Drag the Single Null Mark sheet and drop it into the above container. Hide the sheet title.
Create an open/close button for the container and place the button at the top-right corner.

3. Add annotations

Format the sheet background opacity as 70% in the layout manager
Select area annotations and place them anywhere of interest.
Write help text and format it to highlight important messages.
The text can serve as functional guide and/or insight guide.

Here is an example. Feel free to download the workbook and explore. Click the "i" button at the top-right corner to view the in-place help.

Add a comment

Vizible Difference

In search of data visualization excellence

1. Sheet with a single data mark.

2. Create an show/hide button

3. Add annotations

Add a comment