This is a tale of two visualizations --- one honest and one dishonest. According to the article, the bar chart was created by the German economic development agency GTAI. The article claims that bar charts should start at zero; however, line graphs do not need to do so. These graphs tell different stories: “By its design bar graph emphasizes the absolute magnitude of values associated with each category, whereas a line graph emphasizes the change in the dependent variable (usually the y value) as the independent variable (usually the x value) changes.” The article then describes some examples. Specifically, the article cites a Bloomberg Business Week satire graph which plotted year A.D. on the y-axis against very same quantity on the x-axis, and by suitable choice of scales revealing a flat line.”
The article then claims that multiple axes on a single graph can also be deceptive. The example cited in the article has faults including: (1) bar chart does not start at zero, and (2) lack of distinction between correlation and causation. The author also notes that an axis should not change scales “midstream.” The example the author references shows a 10 unit scale being changed to a logarithmic scale to represent income growth. The author also argues that graph axises must represent numerical data. The author references a graph of the “Top 10 Most In Demand Developer Skills of 2013.” The article ends with the “Worst” graph highlighting an inverted graph which gives the optical illusion that the numbers are decreasing simply because the axis is inverted----(LOL).
Agree/disagree/Curious
I agree that graphs can be [unintentionally] deceptive. One interesting piece is cross-cultural graphic interpretation. For example, some languages read right-to-left rather than left-to-right. I am sure subtle cultural distinctions can affect the human interpretation. I open this question about data visualization across cultures. Can visualization help interpretation? Can visualization harm interpretation? Does one graph fit all cultures?