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Data Visualization

This guide will walk you through what data visualization to use based on your research need and data type

Questions that can be answered by scatter-plots and bubble charts

Scatterplots can answer the following questions:

  • Does x correlate to y?
  • What are the outliers in my data?
  • What are the patterns in my data?

Bubble charts can answer the following questions:

x = x-axis variable, y = y-axis variable, and z = size of the bubble variable.

  • Does x correlate to y? Does x correlate to z? Does y correlate to z?
  • What are the outliers in my data?
  • Are there exceptions to correlations?
  • What are the patterns in my data?
  • What do the position, size, and color of an individual point mean for that data point?
  • How do multiple points compare to each other?
Steelberg, T. (2017). Data Presentation: Showcasing your data with charts and graphs. In K. Fontichiaro, J. A. Oehrli, & A. Lennex (Eds.), Creating Data Literate Students (pp. 165–192). Michigan Publishing.

 

Scatterplot

Definition of scatterplot:

A scatterplot displays the values of a dataset with two numeric variables. each data point is plotted on a grid, where the x-axis indicates one variable, and the y-axis indicates another variable. Oftentimes a line of best fit is drawn to show general trends in the data and the relationship between the variables. 

For additional information, check out https://www.data-to-viz.com/graph/scatter.html

Example of a scatterplots would be these hypothetical ones from https://datavizcatalogue.com/methods/scatterplot.html

scatterplot

Steelberg, T. (2017). Data Presentation: Showcasing your data with charts and graphs. In K. Fontichiaro, J. A. Oehrli, & A. Lennex (Eds.), Creating Data Literate Students (pp. 165–192). Michigan Publishing.

Tips for scatterplots:

  • Correlation does not imply causation: just because correlation seems to exist between two variables does not mean that one causes the other. 
  • If your data points become too dense to read, consider making the points translucent, or using another type of graph. 
  • Scatterplots work best if there is some form of correlation between the two variables. If there is no to little correlation, converting the data to a scatterplot will convey little to no information to your audience. 
  • Look for clusters of points, points that follow a line, and points that are set apart from the rest. These three occurrences indicate important patterns such as frequency, correlation, and outliers. 
  • Label the fit line. 

 

Steelberg, T. (2017). Data Presentation: Showcasing your data with charts and graphs. In K. Fontichiaro, J. A. Oehrli, & A. Lennex (Eds.), Creating Data Literate Students (pp. 165–192). Michigan Publishing.

Bubble Chart

Definition of a bubble chart:

A bubble chart is similar to a scatterplot in the fact that two variables are mapped out along the x- and y- axis. What makes a bubble chart unique is that it adds a third variable by altering the size of the dots to indicate a numeric value. 

Here is an example of a bubble chart from https://visage.co/data-visualization-101-bubble-charts/

Screen Shot 2015-02-04 at 4.41.48 PM

Steelberg, T. (2017). Data Presentation: Showcasing your data with charts and graphs. In K. Fontichiaro, J. A. Oehrli, & A. Lennex (Eds.), Creating Data Literate Students (pp. 165–192). Michigan Publishing.

Tips for a bubble chart:

  • Bubble charts can get crowded because big bubbles can start to overlap: use datasets that don't have too many individual elements to ensure your audience can understand your data visualization. 
  • Label your bubbles, otherwise, your audience will not be able to understand what data elements the bubble refers to. 
  • Use a legend to indicate the meaning of color and size.
  • Bubble charts are best when the audience is comparing individual bubbles, but are difficult to use when determining trends or patterns in the data. 
  • Make sure to use the area of the bubble to indicate size instead of the diameter. 
  • Correlation does not imply causation. 

 

Steelberg, T. (2017). Data Presentation: Showcasing your data with charts and graphs. In K. Fontichiaro, J. A. Oehrli, & A. Lennex (Eds.), Creating Data Literate Students (pp. 165–192). Michigan Publishing.