Cherry-Picking
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[edit] Definition
Cherry-Picking is an expression used to describe the behavior of selecting only the data that confirm the preferred conclusion, ignoring data that contradict it. Cherry-Picking refers to the deliberate exclusion of contrary cases; unconscious exclusion is referred to as Confirmation Bias. Both are forms of Selection Bias.
[edit] Examples
Several studies reported and circulated, mostly among the Christian community, seem to show that prayer can have a positive effect on the healing of someone who has been hospitalized. These studies cherry-picked their data, for example, by selecting the specific malady that showed an improvement in the prayer group, ignoring the rest that showed no difference or even a negative effect.
In a 1998 court ruling (Flue-Cured Tobacco Cooperative Stabilization Corporation et al v. EPA), Judge William Osteen found that the EPA had cherry-picked their data on the exposure of non-smokers to second-hand smoke. He found that the EPA's meta-analysis excluded nearly half of the available studies. Other studies which directly measured the exposure of non-smokers to second-hand smoke resulted in levels of exposure one-twelfth that claimed by the EPA.
Creationist Jim Pinkoski claimed that older fossils are larger, citing 18" cockroaches, 3' dragonflies, 8' beavers, and others. He used this as support for the claim in Genesis 6:4, that there were giants before the flood. He did this by only looking at larger fossils and ignoring the fossils that were the same size or smaller than modern animals.
[edit] Variants
One variant of Cherry-Picking is "Quote Mining", the habit of selecting quotes, usually out of context, to make it appear that the quote´s author holds an opinion that is different (often diametrically opposed) to the one that he actually holds. A common example of this is the creationist practice of quote-mining biologists (including luminaries such as Charles Darwin and Stephen Jay Gould) to the point where they allegedly reject evolution.
For example, in a creationist video, Darwin is quoted as saying:
- Why then is not every geological formation and every stratum full of such intermediate links? Geology assuredly does not reveal any such finely-graduated organic chain; and this, perhaps, is the most obvious and serious objection which can be urged against the theory.
This is used to claim that Darwin doubted his own theory, and that he considered it invalid, or at best just an idea. However, reading the very next sentence shows this to be a deliberate mischaracterization:
- Why then is not every geological formation and every stratum full of such intermediate links? Geology assuredly does not reveal any such finely-graduated organic chain; and this, perhaps, is the most obvious and serious objection which can be urged against the theory. The explanation lies, as I believe, in the extreme imperfection of the geological record.
Darwin then continues to explain why the fossil record did not, at least at his time, plainly show transitionals.
[edit] References
- Skeptico: Prayer still useless
- Flue-Cured Tobacco Cooperative Stabilization Corporation et al v. EPA
- Passive smokers inhale six cigarettes a year
- Pharyngula: If you doubt this is possible, how is it there are PYGMIES + DWARFS??
