There are many different techniques for collecting, interpreting, and analyzing facts, and different techniques often lead to different conclusions, which is why scientists disagree about the dangers of global warming, the benefits of supply-side economics, and the wisdom of low-carbohydrate diets. Good scientists deal with this complication by choosing the techniques they consider most appropriate and then accepting the conclusions that these techniques produce, regardless of what those conclusions might be. But bad scientists take advantage of this complication by choosing techniques that are especially likely to produce the conclusions they favour, thus allowing them to reach favoured conclusions by way of supportive facts. Decades of research suggests that when it comes to collecting and analyzing facts about ourselves and our experiences, most of us have the equivalent of an advanced degree in Really Bad Science.
Daniel Gilbert, Stumbling on Happiness, New York, 2005, p. 164