Assignment 1: Expository Visualization

An expository article requires the author to investigate an idea, evaluate evidence, expound on the idea, and set forth an argument concerning that idea in a clear and concise manner.

In this assignment, you will design an expository visualization to clearly communicate an idea based on a small data set. In addition, you must provide a rigorous rationale for your design choices. You should in theory be ready to explain the contribution of every pixel in the display towards your expository goals. You are free to use any graphics or charting tool you please — including drafting by hand.

(See Resources for a list of visualization tools.)

Data Set: Monthly Hours of Sunshine in Major U.S. Cities

The climate of a place can have a tremendous impact on people's lived experience, ranging from personal moods to how an entire region defines itself. Here, you will examine a set of average monthly climate measurements for six major U.S. cities, roughly covering the edges of the continental United States. This is the same dataset you worked with in Activity 1.

For more information about the dataset, including download links for CSV and JSON formats, see https://observablehq.com/@uwcse-datavis/hours-of-sunshine.

Assignment

Your task is to design a static (i.e., single image) visualization that you believe effectively communicates an idea about the data, and provide a short write-up (no more than 4 paragraphs) describing your design. Start by choosing a question you'd like your visualization to answer. Design your visualization to answer that question. The title of your graphic should either be your question or your answer to the question that the chart conveys.

Be sure to pick a question and visualization design that meaningfully differs from the line and bar chart designs considered in Activity 1.

While you must use the data set given, you are free to transform the data as you see fit. Such transforms may include (but are not limited to) log transformation, computing percentages or averages, grouping elements into new categories, or removing unnecessary variables or records. You are also free to incorporate additional external data. Your chart image should be interpretable without recourse to your write-up. Do not forget to include title, axis labels, or legends as needed!

As different visualizations can emphasize different aspects of a data set, your write-up should document what aspects of the data you are attempting to most effectively communicate. In short, what story are you trying to tell? Just as important, also note which aspects of the data might be obscured due to your visualization design.

In your write-up, you should provide a rigorous rationale for your design decisions. A good way to do this is to document the visual encodings you used and explain why they are appropriate for the data and your specific question. What kinds of visual comparisons and trends do you want to communicate to the viewer? Do your design choices support them? These decisions include the choice of visualization type, size, color, scale, and other visual elements, as well as the use of sorting or other data transformations. It can be helpful to use Mackinlay's effectiveness rankings from the visual encoding lecture (10/8) to justify choices.

Although you will only upload a single chart to Gradescope, you are strongly encouraged to experiment with multiple visualizations that utilize different encoding schemes to answer the same question. A good submission will utilize encodings that are defensible for answering your chosen question. A great submission will use and argue for the encodings that are best suited to the task.

Grading

The assignment score is out of a maximum of 10 points. We will determine scores by judging both the soundness of your design and the quality of the write-up. We will also look for consideration of audience, message, and intended task. We expect that a typical submission will score between 8.5 and 9.5 points out of 10. A rough rubric is:

• Choice of question (1 point): You will receive 0.5 points for choosing a question that meaningfully differs from Activity 1. The remaining 0.5 points are reserved for exceptionally creative choices of question, especially those that incorporate external data.
• Labels/Title/Legend (1 point): Axes should be labeled and should clearly communicate any unit information. The chart should contain a title as described above. As a general rule, between axis labels, chart titles, and legends, we should not need to read your write-up to understand what is being conveyed in the visualization.
• Graphic Quality (1 point): Your image should be submitted at a reasonable resolution, and fonts should be readable.
• Data Transformations (1 point): Any data transformations (e.g. averages, log-scaling, taking a max) used should be appropriate for the task. Its OK if your final visualization does not rely on any/many transformations.
• Marks and Encodings (3 points): The marks and encodings used in the visualization should be reasonable for the kinds of data you are working with. Ideally they should be those that are best suited to the central task. You are encouraged to test out a few alternate encoding schemes before settling on the visualization you submit.
• Write-up (3 points): Your write-up should attempt to justify all major design decisions. Your write-up should clearly convey the story you are attempting to tell with your visualization or the answer to the central question behind the visualization. It is OK if your results are inconclusive or do not show a clear trend, so long as your describe what your visualization shows about the data.

Submission Details

This is an individual assignment. You may not work in groups. Your completed assignment is due on Tue 10/13, by 11:59pm. We will be discussing submissions in class, so be sure to avoid a late submission if at all possible.

You must submit your assignment using Gradescope. Your submission will consist of: (1) your visualization design (as a PNG or JPG image file), and (2) your writeup, without your name or UW NetID (either uploaded in a plain text file "readme.txt" or written in the free response box).

Please use the correct file extension for your image (either .png or .jpg) and be sure your image is sized for a reasonable viewing experience. Viewers should not have to zoom or scroll in order to effectively view your submission!

If you are on the waiting list for the class and do not have access to the Gradescope site, please email your submission to us at cse442@cs.washington.edu.