lies, damned lies, and graphs

From Ronald Rychlak of the Heartland Institute, a report on the ways in which visual aids (e.g., graphs) can be misunderstood &/or twisted in order to make evidence look far more compelling-- with application to the global warming debate...

From the executive summary:

A new study on the use of visual exhibits in the global warming debate--a tactic employed regularly by former Vice President Al Gore in his film, An Inconvenient Truth--reveals how graphs, charts, and other images can be accurate and still skew data to support a partisan view....

Author Ronald J. Rychlak notes, “Advocates have ‘packaged’ their evidence with charts, graphs, and other visual exhibits designed to have maximum impact with minimal effort on the part of the public. The manipulation of visuals--bar and line graphs, pie charts, even photographs--has proven to be a highly effective way to offer up scary scenarios ... and it is easily done.

And excerpts from the paper itself...

Global warming involves science, economics, and politics. Each of these areas has its own complexities, and there are many difficult issues and sub-issues. Moreover, special interests on both sides of the debate can make the case more difficult to understand rather than easier.

One problem with the global warming theory is that there is no way to use the scientific method to test the link between carbon dioxide and temperature levels at an atmospheric scale. A scientist cannot emit carbon dioxide into some atmospheres and leave others as an experimental control. We have only one atmosphere to work with and we are dependent on it for our lives. The scientist is left with environmental modeling—sort of reverse engineering. This involves looking at changes that have taken place and trying to figure out why they happened. This is a recognized way to try to understand the world, but it is far less certain than experimentation based on the scientific method.

See also: many supposed examples of evolution-- and especially, Evolution as a comprehensive explanation for the development of life.

There are some things in the climate change debate on which there is widespread agreement. Average global temperatures have increased by about one degree Celsius over the past 100 years. During the second half of that period, carbon emissions from human activity increased significantly, and the amount of carbon dioxide in the atmosphere has increased from about 280 ppm to 380 ppm, or from approximately 0.03 percent of the atmosphere to 0.04 percent of the atmosphere. Whether this amount of a “trace gas” actually could lead to a global temperature increase is where much of the modern debate is focused.

Environmental activists may be tempted to exaggerate their case in order to convince the public and politicians of the validity of their scenarios. This was illustrated in a statement made by climatologist Stephen H. Schneider, one-time adviser to Vice President Al Gore and author of the book Global Warming: Are We entering the Greenhouse Century? (1989). Schneider said that in order to reduce the risk of potentially disastrous climatic change, “we have to get some broad-based support, to capture the public’s imagination. That, of course, entails getting loads of media coverage. So we have to offer up scary scenarios, make simplified dramatic statements, and make little mention of any doubts we might have.”

The manipulation of visuals—bar and line graphs, pie charts, even photographs—has proven to be a highly effective way “to offer up scary scenarios” ... and it is easily done. This report explains how visuals can be manipulated by, among other techniques:

-changing the appearance of graphs by adjusting baselines (minimums) and maximums on the vertical axis;

-selectively reporting data on, for instance, a time line appearing on the horizontal axis of a chart;

-using color and three dimensions to call attention to specific elements of a graph, even when those elements may not warrant special treatment; and

-inaccurately superimposing graphs with different scales.

More than a dozen visuals throughout this report, including many that are common to the current debate over global warming, make it easy to see the effect of manipulated visuals....

I don't reproduce any of those here, but they're worth checking out if you've read this far!