Three statistical goods

Conducting scientific studies is never easy, and there are often large disasters on the way. A researcher accidentally spreads coffee on a keyboard, destroying the data. Or one of the chemicals used in analysis is contaminated, and the list continues.

However, when we read the results of the study in a scientific paper, it always looks ancient. The study went easily without hiccups, and here are our results.

But the study may have errors, all of which are not weeds before publication of independent experts or “colleagues”.

It can be difficult to find statistical goods-ups because it actually takes someone trained in data to do some wrong notice.

When statistical mistakes are made and found, it can have a profound impact on those who may have changed their lifestyle as a result of defective study.

These three examples of unknown statistical mistakes are the major results for our health and shopping habits.

1. Did you throw your black plastic spoon?

At the end of last year, I came across News article How black plastic kitchen utensils were dangerous because they could potentially leak toxic flame-retardant chemicals in your food.

Being a natural suspicion, I saw the original paperWhich was published in the magazine ChemistThe article looked real, the magazine was distinguished. So – perhaps many other people – I threw my black plastic kitchen vessel and replaced them with silicon.

In the study, the authors examined 203 domestic products (about half kitchen utensils) made of black plastic.

The authors found the toxic flame retarded in 85% of the tested products, which have levels with maximum daily levels. Limit Determined by the Environment Protection Agency in the United States.

Unfortunately, writers made one Mistake In their calculation. They were out of a factor of 10. This meant that the level of toxic chemicals was well under daily security boundaries.

In recent weeks, writers Apologized and corrected Their paper.

2. Did you escape from HRT?

A Landmark study Security concerns about hormone replacement therapy or HRT (now also known as menopausal hormone therapy). It highlights a different type of statistical error.

Women’s Health Initiative (WHI) Study 10,739 postmenopause women aged 50–79 from 40 clinical centers in the US were included. It compared the health of those who were randomly random to take HRT with those who took placebo. Neither researchers nor women knew which treatment was given.

His 2002 paperAuthors reported high rates of aggressive breast cancer in the HRT group. He used a unit called “person-year”. The person-year is a way to measure the total time that a group of people spends in a study. For example, if 100 people are in a study for one year, it makes 100 persons. If anyone leaves the test only after six months, it is counted for them only for that half year.

The authors showed 38 aggressive breast cancer rates per 10,000 persons in HRT group-10,000 per year, while in the placebo group 30 per 10,000 persons per year. It gives the rate ratio of 1.26 (one rate divided by another).

It was also expressed as a large increase in the rate of breast cancer, 26% increase, which made it prevalent Nervousness Worldwide, and thousands of women stopped HRT.

But the actual risk of breast cancer in each group is low. The rate of 38 per 10,000 person-year is equal to an annual rate of 0.38%. With such low rates, writers should actually use Rate difference Instead rate ratioThe rate difference is reduced by one rate from another, instead of dividing by it. This is equal to the annual growth of 0.08% breast cancer cases in HRT group – much more modest.

The 2002 paper writers also reported that the rate of breast cancer increased by 26% “almost nominal statistical importance.” About There is no statistical importance, and formally, it means that there was no difference in the rate of breast cancer between the two groups. In other words, the difference between the two groups could have been coincidentally.

Writers should have been more careful when describing their results.

3. Did Popi’s spinach change your food?

The cartoon character pope is a single, pipe-dhumrapan, a sailor, with the English in love with Willoli Olive Ol. He is constantly in trouble, and when he needs additional energy, he opens a can of spinach and swallows the material. His biceps are immediately emerged, and he goes to solve the problem.

But why does Popi eats spinach?

Story About 1870 begins, with a German chemist, Erich von vulf or amil von Wolf, on the basis of which Version of events you read.

He was measuring the amount of iron in a variety of leafy vegetables. according to legend, Whatever controversyHe was writing the iron content of spinach in a notebook and misunderstood the decimal point, writing Service of 3.5 mg per 100 grams of spinach instead of 35 mgThe error was found in 1937 and he was corrected.

By then the pope character was created and the spinach became incredibly popular with children. ObviouslyConsumption of spinach in the US resulted in a third of the cartoon.

This story achieved mythological status but is small MistakeIn a 1932 cartoon, Pope explains why he eats spinach, and it has nothing to do with iron. He says in his proud English:

“Spinach is full of vitamin A.

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