成为科学家有点像侦探。科学家看问题或困境，然后收集证据以形成结论。我们的社会依靠科学家在结论中是正确的。例如，科学家每年都会开发新的流感疫苗，以保护我们免于生病。为此，他们必须进行实验，以找出哪些流感病毒菌株最有可能影响当年的人群。一旦他们收集了足够的实验证据，就会产生一种流感疫苗，可为这些菌株提供最有效的保护。我们依靠这些科学家形成正确的结论，并开发正确的流感射击，以保护我们所有人免受疾病的侵害。但是，他们如何确保他们发现的答案是正确的？
这是实验设计进入图片的地方。
What is experimental design?
实验设计就是计划实验，以确保结果是客观和有效的。由于实验是科学发现的基本组成部分，因此我们必须很好地设计它们绝对至关重要。设计较差的实验不会提供任何证据来支持特定结论，甚至可能指出不正确的结论。
Take a look at the graph below, published by theNew England Journal of Medicine，其中比较了20个国家 /地区的人均巧克力消费奖与每年巧克力消费的数量。
该图显示了巧克力消费和诺贝尔奖赢得的明显相关性。您可能会查看此图提供的证据，并得出结论，吃巧克力使您更有可能赢得诺贝尔奖，甚至可以使巧克力更加聪明。
However, the graph fails to take into account other factors that might affect winning a Nobel Prize, such as education standards in each country, or the available research funding. This is a classic example of mistaking correlation for causation. A well-designed experiment would account for those other factors, using positive and negative controls to measure whether chocolate actually influences the likelihood of winning a Nobel Prize.
您如何计划有效的实验？
Step 1: Ask a question
All scientific research starts with a question that you want to answer. For example, does eating chocolate increase intelligence?
步骤2：提出假设
您的假设是对研究问题的可检验解释。您设计的实验将提供证据表明支持或反驳该假设。注意不要将假设与预测混淆。一个预测是你的想法will happen将来，虽然假设可能是对什么的解释is happeningnow.
A hypothesis could be something like: Eating two ounces of chocolate per day increases IQ.
Step 3: Choose the experimental model
The experimental model is the technique and sample you use to test your hypothesis. In other words, what tests you’ll perform, and what test subjects you’ll use. Some experiments use plates of cells, some use mice, some use computer programs, and others use humans. It all depends on what you’re testing!
There are many experimental models, and you should try to choose the most effective one for your experiment.
Step 4: Define variables
Once you have an experimental model to test your hypothesis, you need to define which variable you want to measure. In an experiment, there is generally a dependent variable and an independent variable. Independent variables are controlled by the experimenter. Dependent variables are what you measure in response to changes in the independent variable. In our example, the independent variable is the amount of chocolate consumed, and the dependent variable is the measured change in IQ.
步骤5：创建控件
Experimental controls allow you to be more certain that the independent variable is responsible for the changes in the dependent variable. There are two kinds of controls: you expect a known response in positive controls, and expect no response in negative controls. A positive control would have to be a treatment that is known to increase IQ, such as proven brain training exercises, while a negative control would be a lack of treatment altogether.
步骤6：执行实验
Now it’s time to experiment! Run your tests on the test groups, positive controls, and negative controls, and record the results.
Step 7: Analyze the results
查看结果数据并分析。您的数据是否支持您的假设？
Step 8: Repeat!
Once you have carried out your experiment with controls, you will have an idea of whether or not your hypothesis is correct – but that still isn’t proof! We can only make conclusions if the experiment is reproducible and the results are consistent over several replications. Once you have performed the experiment several times and observed similar results,thenyou can analyze the data and start to draw conclusions.
About the Experimental Design virtual lab simulation
The best way to learn how to design a scientific experiment is to try it yourself. In theExperimental Design simulation, you will step into the shoes of a pharmaceutical detective for a day. Your task is to design and carry out an effective experiment to find out if a new drug is causing damage to kidney cells.
这是您在下面的模拟中介绍的主题的简要概述。
The scientific method
人类一直在努力解释自然现象。在第一个任务中experimental design simulation, you will do just that. The scientific method gives you a practical template for forming and testing conclusions. Using it, you can investigate phenomena, acquire new knowledge, or correct and integrate existing knowledge surrounding your experiment.
Design an experiment
在你的下一个任务,你有德的自由gn your own experiment from scratch while examining human kidney cells under a microscope. Every tool you need to design and perform your experiment is available inthis virtual lab.
你会：
Choose an experimental model:Choose the correct experimental model from yeast cells, mice, human samples, or kidney cell lines, to design a scientifically sound experiment for testing the effect of the suspicious drug. And don’t be afraid to make mistakes – in this virtual simulation you can repeat the experiment as many times as you want.
Define the dependent and independent variables:Based on your experimental model, which variable will you be manipulating as the experimenter? What will you be measuring?
Create controls:阳性和阴性对照将帮助您得出结论，可疑化合物是否可能是报道流行病的原因。与仅使用缓冲液的阴性对照相比，您可以研究药物中化合物的作用，以及用已知会导致肾脏损伤的化合物处理的阳性对照。
Perform the experiment:将处理添加到阳性对照，阴性对照组和实验组后，使用实验室设备观察每个实验组的因变量的变化。
分析结果并介绍您的发现：Look at your data, and decide whether or not it supports your hypothesis. Then present the results of your experiment at a meeting with a virtual professor.
Are you ready to set up your own experiment and test the side effects of a suspicious new drug? Click the button below!
