Statistical correlation is not the same as cause and effect

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Statistical correlation is not the same as cause and effect

Recent media coverage about ingredients in biscuits causing allergic reactions in atopy sufferers and contact lens solutions triggering bacterial keratitis, an inflammation of the cornea, led to outbursts of concern among parents and contact lens wearers.
“Can we give our children biscuits?” mothers asked.
“Can we use contact lens solution? We heard that it results in eye infections,” contact lens wearers wondered.
It would be undesirable to make hasty decisions not to use the solutions or to give up eating biscuits. There first needs to be a process of verification.
A recent television program portrayed children whose allergic reactions were aggravated after eating biscuits. Through clinical tests, the program concluded that ingredients in the biscuits were the cause of the aggravation. This may be correct. However, there needs to be a distinction between “causes” and “aggravating factors.”
For example, if oil is a cause, a match is an aggravating factor. But without oil, the match cannot start a fire. The causes of atopy are not well understood, even by doctors, but the aggravating factors are well defined. Food additives are not the only aggravating factors. Even milk, fish and beans can aggravate atopy. There are hundreds of such factors and it is impossible to avoid all of them. Even in Australia and New Zealand, where the environment is less polluted than in Korea, the number of atopy cases is increasing. The Korea Drug and Food Administration began clinical research on whether food additives cause atopy. Thus we need to wait for the conclusion of the study. If a child does not have atopy, there is no reason to stop eating biscuits. Even if a child has atopy symptoms, but symptoms are not affected by biscuits, again he does not have to stop eating them.
The issue of contact lens solution is a question of “statistical correlation” or “cause and effect.”
A few years ago, statistical research showed that people with corns on the soles of their feet live longer. But do corns really contribute to long life? There is a statistical correlation between corns and the duration of life, but that is not cause and effect.
The case regarding contact lens solution is also an issue of statistical correlation. The Center for Disease Prevention and Control in the United States did not make the conclusion that contact lens solution and eye infections are a matter of cause and effect. It also did not order a recall of the products. In addition, the bacteria that cause keratitis are a type that is easily found in Florida. Thus, this is unlikely to be a big problem in Korea.
It is not necessary to throw away your biscuits or contact lens solutions yet.


by Hong Hye-gul
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