Sources Contact Advanced Search Tutorials

An Interest In:

Web News this Week

Search Archive

Some of Our Sources

View All Sources

Help Webnuz

Referal links:

August 23, 2019 04:47 pm

Graphics That Seem Clear Can Easily Be Misread

An anonymous reader shares a report: "A picture is worth a thousand words." That saying leads us to believe that we can readily interpret a chart correctly. But charts are visual arguments, and they are easy to misunderstand if we do not pay close attention. Alberto Cairo, chair of visual journalism at the University of Miami, reveals pitfalls in an example diagrammed here. Learning how to better read graphics can help us navigate a world in which truth may be hidden or twisted. Say that you are obese, and you've grown tired of family, friends and your doctor telling you that obesity may increase your risk for diabetes, heart disease, even cancer -- all of which could shorten your life. One day you see this chart. Suddenly you feel better because it shows that, in general, the more obese people a country has (right side of chart), the higher the life expectancy (top of chart). Therefore, obese people must live longer, you think. After all, the correlation (red line) is quite strong. The chart itself is not incorrect. But it doesn't really show that the more obese people are, the longer they live. A more thorough description would be: "At the national level -- country by country -- there is a positive association between obesity rates and life expectancy at birth, and vice versa." Still, this does not mean that a positive association will hold at the local or individual level or that there is a causal link. Two fallacies are involved. First, a pattern in aggregated data can disappear or even reverse once you explore the numbers at different levels of detail. If the countries are split by income levels, the strong positive correlation becomes much weaker as income rises. In the highest-income nations (chart on bottom right), the association is negative (higher obesity rates mean lower life expectancy). The pattern remains negative when you look at the U.S., state by state: life expectancy at birth drops as obesity rises. Yet this hides the second fallacy: the negative association can be affected by many other factors. Exercise and access to health care, for example, are associated with life expectancy. So is income.

Slashdot

Slashdot was originally created in September of 1997 by Rob "CmdrTaco" Malda. Today it is owned by Geeknet, Inc..

More About this Source Visit Slashdot