Health Economics

Detailed description of, "Evaluating Sources: 6 Question Words"

Data, like other information you use in your paper, is evidence to support your thesis. Therefore, you must evaluate data just as you would any other supporting information, such as a scholarly article, webpage, or document. Think of the 6 question words (who, what, where, when, why, and how) when deciding whether to use the data as evidence in your paper. For example, who produced the data? Are they trustworthy? Was their method of obtaining or creating the data credible?

If you are using summary-level data (a chart or graph from a book, website, or scholarly article) you MUST analyze it carefully before you use it. There is a lot of bad data visualization out there and, if you interpret it incorrectly and then use it to bolster your argument, the rest of your writing becomes suspect as well.

If you are using the micro-level or raw data for your analysis, this is less of an issue and you, as the creator of the data visualization need to make sure you keep these ideas in mind.

Reading the data:

1. Determine how the figure/table is set up.
   • What are units on the axes (for a figure) or heading of the columns (for a table)? Make sure you understand what these units mean.
   • Pay attention to the symbols on a figure. For example, the differences between dotted and solid lines.
   • If there is a data dictionary or codebook, it is helpful to review it.
   • If it is generated by a database, be aware that some use algorithms to determine data points. These can be proprietary and secret, so you may not know exactly how the data is being calculated.
2. Now look at the pattern in the data.
   • For a figure with lines, what is their pattern? Do they increase, decrease, increase or decrease and then then level off? In a table do the numbers increase or decrease across the column?
3. Examining tables, graphs, and charts carefully should give you a good idea of the question addressed by the data and the methodology (e.g., experiment, survey, etc.) done to get the data.

Interpreting the data:

1. What conclusions can you draw from the pattern that you have described?
2. What do these results tell you about what is being studied?
3. How do they fit into the larger picture of the discipline?

Note: Interpretations can differ from person to person. This is part of why interpreting data is tricky.

Text adapted from Ecoplexity, "Interpreting Figures and Tables." Portland State University (2010). http://ecoplexity.org/?q=interpreting_graph_table.

EXAMPLE : When a chart is not what it seems to be.

The chart on the left, below, was used in 2015 by Republican Representative Jason Chaffetz of Utah, during the U.S. House Committee Hearing on Planned Parenthood. Look closely at the two lines, they cross each other but are widely different figures.

The chart on the left is the original chart. The chart on the right is with the data graphed more accurately. Even then, the numbers are so different from the top line to the bottom line that they appear skewed even in the graph on the right. This is bad data visualization.

Image on the left from: http://www.dailykos.com/story/2015/9/29/1426029/-I-ve-corrected-the-chart-Rep-Chaffetz-presented-at-today-s-Planned-Parenthood-hearing

More Examples