Evaluating Data Visualizations Thank Susan Introduce myself Questions answered at end Evaluating Data Visualizations Steve Fleming, Senior Systems Analyst, National Center for Educational Achievement a department of ACT, Inc., a not-for-profit organization committed to helping people achieve education and workplace success.

The use of images to represent information Data Visualization The use of images to represent information

XYZ District We went through a systematic process to improve our data presentation in CWD 3

Best practice research Evaluation Based On… Best practice research Focus groups

Best practice research Evaluation Based On… Best practice research Focus groups

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Table vs. Graph Use a table when… The document will be used to look up individual values. It will be used to compare individual values. Precise values are required. The quantitative information to be communicated involves many units of measurement. Use a graph when… The message is contained in the shape of the values. The document will be used to reveal relationships among multiple values. Source: Stephen Few, Show Me the Numbers, p46.

Edward Tufte Above all else show the data Subtract unnecessary ink Emphasize the most important data ink Mute and regularize non-data ink Advocate for excellence in graphic design Source: Stephen Few, Show Me the Numbers, pp114-115. http://www.edwardtufte.com/tufte/

Graph Example The legend (non-data ink) stands out too much, move to header

Graph Example Gridlines (non-data ink) are too dark Data lines too thin in comparison

Graph Example Lines do not have to be distinguished by color and point shape (unecessary ink) Use lines to emphasize the trend

Graph Example Maybe we are only interested in the deviation between the lines (unecessary ink) See Stephen Few, Now You See It

Graph Example Now can add more lines! (emphasize the data!)

Graph Example Insights 1. Pattern is similar across grade levels i.e. the whole school rose and fell in the same year not better/worse cohorts moving through the system 2. Grade 5 has the smallest opportunity gap (this school’s students show positive growth across grades)

Graphic Excellence Published: November 6, 2009 http://www.nytimes.com/interactive/2009/11/06/business/economy/unemployment-lines.html Published: November 6, 2009 The Jobless Rate for People Like You Not all groups have felt the recession equally. Learned about through AEA weekly update 240 trend lines ~8,000 data points Select a category Browse the lines

The National Center for Educational Achievement Contact The National Center for Educational Achievement 8701 North MoPac Expressway, Suite 200 Austin, TX 78759 512.320.1800 www.nc4ea.org Steve Fleming sfleming@nc4ea.org Questions?