Psychology, 5/e   Wortman, Loftus & Weaver
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Frequently Asked Questions

1. Does a correlation imply a cause and effect relationship?

This is one of the most common misrepresentations of research by the popular media. The problem stems from this: in many correlational studies, one variable probably does causes changes in the other! For example, correlational studies linking smoking and cancer have been reported for decades. Ultimately, through a variety of techniques, this causal relationship was indeed confirmed. But in and of themselves, correlational studies only link variables; they cannot establish actual cause and effect. Take the recent widely-reported evidence that those who drink modest amounts of red have reduced incidence of cardiac disease. Is the reduction of cardiac problems caused by the red wine? Maybe not. Perhaps it is caused by the relaxation induced by the red wine. Maybe the wine alters the way in which food is digested. You can probably come up with many other possible hypotheses. Correlation is an invaluable research tool, but don’t make the common error of assuming correlation can show causation.

2. What are the most important ideas still to be researched and understood in behavioral genetics?

Perhaps the two greatest challenges still to be understood are the apparently small effects of ES (shared environmental effects; the effect of family environment) and the degree to which one’s environmental effects are actually influenced by genetic predisposition. That is, those who are quiet and introverted tend to select environments which minimize social contact--thereby reinforcing their inherited personality characteristics.

3. I once heard someone say that there are "lies, damn lies, and statistics," implying that statistics are easily manipulated and cannot be trusted. What truth is there to this?

Statistics should be used as a tool to examine and evaluate evidence. Instead, they are often used as “proof” of a certain idea or theory. If a researcher has a particular bias or agenda, then statistics are often selectively applied (or reported). Used this way, statistics can be used incorrectly (even unethically) to present misleading evidence.

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