Not all scientific studies are created equal - David H. Schwartz

不是所有科学研究都是等价的 - David H. Schwartz

翻译人员: Cora Liu 校对人员: Qingqing Mao

Studies have shown that

研究表明，

taking vitamins is good for your health

吃维生素有利于健康，

and bad for your health.

也有害于健康。

That newly discovered herb can improve your memory

最新发现的一种药草可以增强记忆力，

or destroy your liver.

或者损害你的肝脏。

Headlines proclaim a promising new cancer treatment

头条新闻报道了一种前景光明的癌症治疗方法，

and never mention it again.

接着却再也没有提及。

On a daily basis,

每天

we are bombarded with attention-grabbing news,

我们被吸睛的新闻所轰炸，

backed up by scientific studies,

它们都有科学研究的支持，

but what are these studies?

但这些研究到底是什么？

How are they performed?

它们是如何进行的？

And how do we know whether they're reliable?

我们怎么知道它们是否可靠？

When it comes to dietary or medical information,

当涉及饮食和医疗信息时，

the first thing to remember

首先需要记住的是，

is that while studies on animals or individual cells

虽然实施在动物或单个细胞上的研究

can point the way towards further research,

可以引导未来的研究，

the only way to know how something will affect humans

但想知道它们如何影响人类的唯一方法

is through a study involving human subjects.

是通过一个有人体参与的研究。

And when it comes to human studies,

当涉及人体研究的时候，

the scientific gold standard is

科学的黄金标准就是

the randomized clinical trial, or RCT.

随机临床试验，或者叫RCT。

The key to RCTs is that the subjects are randomly assigned

RCT的关键是

被试者被随机分配到各个研究组。

to their study groups.

They are often blinded to make them more rigorous.

他们通常是不知情的，这样可以使研究更加严谨。

This process attempts to ensure

这个过程是为了保证

that the only difference between the groups

不同组之间的唯一区别

is the one the researchers are attempting to study.

是研究者想要研究的东西。

For example,

举个例子，

when testing a new headache medication,

当测试一种全新的治疗头痛的药物时，

a large pool of people with headaches

一大群有头痛问题的人

would be randomly divided into two groups,

会被随机分配到两组，

one receiving the medication

一组得到治疗的药物，

and another receiving a placebo.

另一组得到安慰剂。

With proper randomization,

在正确的随机分配下，

the only significant overall difference

两组间

between the two groups

唯一显著的区别

will be whether or not they received the medication,

就是他们有没有得到药物，

rather than other differences that could affect results.

而不是其他会影响结果的因素。

Randomized clinical trials are incredible tools,

随机临床试验是非常有用的工具。

and, in fact, the US Food and Drug Administration

事实上，美国食品及药物管理局（FDA）

often requires at least two to be conducted

通常要求在新药上市前

before a new drug can be marketed.

要进行至少两次随机临床试验。

But the problem is that an RCT is not possible

但是问题是在很多案例里

随机临床试验是不可能的。

in many cases,

either because it's not practical

这可能是因为它不切实际，

or would require too many volunteers.

或者是因为需要过多的志愿者。

In such cases,

在这类情况下

scientists use an epidemiological study,

科学家们使用一种流行病学研究，

which simply observes people going about their usual behavior,

它简单地观察人们的日常行为，

rather than randomly assigning active participants

而不是通过随机分配主动参与者

to control invariable groups.

来控制不变量。

Let's say we wanted to study

假设我们想研究

whether an herbal ingredient on the market

一种市场上的草药成分

causes nausea.

是否会引起恶心。

Rather than deliberately giving people something

我们不会故意给人们

that might make them nauseated,

一些可能造成他们恶心的东西，

we would find those who already take the ingredient

而是找到那些在日常生活中

in their everyday lives.

已经服用了这种成分的人。

This group is called the cohort.

这个组叫做队列。

We would also need a comparison group

我们还需要一个比较组，

of people who do not have exposure to the ingredient.

他们并没有接触过这种成分。

And we would then compare statistics.

接着我们就要比较数据。

If the rate of nausea is higher in the herbal cohort,

如果恶心程度在草药队列里面偏高，

it suggests an association

它就表明了在草药成分和恶心之间

between the herbal supplement and nausea.

有一种联系。

Epidemiological studies are great tools

流行病学研究非常有用，

to study the health effects of almost anything,

可用于研究几乎任何东西对健康的影响，

without directly interfering in people's lives

而不需要直接干扰人们的生活，

or assigning them to potentially dangerous exposures.

也不会让人们接触到有潜在危险的东西。

So, why can't we rely on these studies

那么，我们为什么不依赖这些研究

to establish causal relationships

来研究物质和它们对健康的影响

between substances and their effects on health?

之间的因果关系？

The problem is

问题是

that even the best conducted epidemiological studies

即使是实施得最好的流行病学研究

have inherent flaws.

也存在内在的缺陷。

Precisely because the test subjects

准确的说是因为被试者

are not randomly assigned to their groups.

不是被随机分配到他们的组别的。

For example, if the cohort in our herbal study

比如在我们的草药研究中，

consisted of people who took the supplement

如果队列是由那些因为健康原因

for health reasons,

而服用草药成分的人所组成的，

they may have already had higher rates of nausea

他们可能本身就比在另一个组里的人

than the other people in the sample.

更有可能感到恶心。

Or the cohort group could've been composed of

或者说队列组有可能

people who shop at health food stores

由那些在健康食品商店购物的人组成，

and have different diets

或者由不同饮食习惯的人组成，

or better access to healthcare.

或者由那些享有更好的医疗保健的人组成。

These factors that can affect results,

这些在被研究因素之外

in addition to the factor being studied,

也可能影响到结果的因素，

are known as confounding variables.

被称为混肴变量。

These two major pitfalls,

这两个主要的缺陷

combined with more general dangers,

加上更多的常规性问题——

such as conflicts of interest or selective use of data,

比如利益冲突或是选择性地使用数据，

can make the findings of any particular epidemiological study suspect,

能让任何流行病学的发现变得可疑。

and a good study must go out of its way

而一个好的研究必须不厌其烦地

to prove that its authors have taken steps

来证明它的研究者采取了必要的步骤

to eliminate these types of errors.

来消除各种类型的错误。

But even when this has been done,

但是，即使这些都做到了，

the very nature of epidemiological studies,

流行病学研究的本质

which examine differences between preexisting groups,

是研究已经存在的不同组别的差异，

rather than deliberately inducing changes within the same individuals,

而不是在相同群体内特意加入差别。

means that a single study

这意味着一个单独的研究

can only demonstrate a correlation

只能证明

一种物质和一个健康结果之间的一种关联，

between a substance and a health outcome,

rather than a true cause and effect relationship.

而不是一个真的因果联系。

At the end of the day,

最后我想说，

epidemiological studies have served as excellent guides to public health,

流行病学研究在公共健康中起到了非常大的指导作用，

alerting us to critical health hazards,

警告我们某些严重的健康威胁，

such as smoking, asbestos, lead, and many more.

比如吸烟、石棉、铅，还有更多。

But these were demonstrated through

但是这些都是通过

multiple, well-conducted epidemiological studies,

多个实施良好的流行病学研究来证明的，

all pointing in the same direction.

而所有这些研究都指向同一结果。

So, the next time you see a headline

所以，下次你看到一个头条新闻

about a new miracle cure

关于某种全新神奇的治疗，

or the terrible danger posed by an everyday substance,

或是关于某种日常用品产生的可怕威胁，

try to learn more about the original study

试着去看一下原始的研究，

and the limitations inherent in any epidemiological study or clinical trial

去了解流行病学研究和临床试验中内在的局限性，

before jumping to conclusions.

而不是直接跳过去读结论。