Data Viz Done Right

April 13, 2021

How to Calculate a Z-Score

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A Z-score is a numerical measurement that describes a value's relationship to the mean of a group of values. Z-score is measured in terms of standard deviations from the mean. 

  • If a Z-score is 0, it indicates that the data point's score is identical to the mean score. 
  • A Z-score of 1.0 would indicate a value that is one standard deviation from the mean. 
  • Z-scores may be positive or negative, with a positive value indicating the score is above the mean and a negative score indicating it is below the mean. 

The calculation you need is Tableau is: 

( SUM([Profit]) - WINDOW_AVG(SUM([Profit])) ) 

Replace the SUM([Profit]) with whichever measure you'd like to use at the aggregation that makes sense in your data. 

Get the data used in the video here -

April 12, 2021

#MakeoverMonday 2021 Week 15 - Fouls Called by NBA Referees

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The original viz for this week was so good that I struggled to come up with something different. In the end, I wanted to learn by recreating the original. Check out #WatchMeViz and interact with the viz below.

April 8, 2021

How to Create a Ternary Graph / Triangular Chart

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Ternary graphs visualise the ratios between the three variables. A ternary graph requires three metrics, plotted as a triangle, where the sum of all three variables adds up to a constant. You can think of it as a three dimensional scatterplot. 

Each dimension is plotted based on its relative variance (on a scale of 0%-100%) to the largest value within the dimension. 

A value plotted near the top would indicate a weighting towards the variable at the top. Likewise, for the bottom right, a value plotted there would indicate a weighting towards the variable that was plotted on the bottom right. A value in the middle, indicates the dimension is balanced across all three variables.

Download the Car Sales mock data set here. Download the triangle I used as the background image on the chart here.

April 5, 2021

#MakeoverMonday 2021 Week 14 - Multiclass Classification of Dry Beans

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