1. 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.

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

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

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

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

6. Show Me the Numbers http://www.perceptualedge.com/
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7. 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.

8. 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, pp

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

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

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

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

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

14. 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)

15. Graphic Excellence Published: November 6, 2009
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

16. The National Center for Educational Achievement
Contact
The National Center for Educational Achievement
8701 North MoPac Expressway, Suite 200
Austin, TX 78759
Steve Fleming
Questions?