Take a moment to understand the terms. Words like placebo, randomization, and double-blind we have heard before, and often, we think we know what it means. But if you had to come up with the definition, say when your ten-year-old asks, how would you define it? Let's start with a scenario:
Imagine you wanted to conduct an experiment on whether chocolate improved the mood of normal people.
- First, you would gather a representative sample of people. This means that these people fairly represent the population in terms of diversity, economics, etc. If you only got oompa-loompas, they wouldn’t be representative to human beings across the spectrum. You then test them to ensure that they fall within normal, healthy guidelines. Then you would begin your experiment.
- An experiment is simply a controlled environment wherein a concept is tested to see if it can be proved.
- The experimental group is the group of people or animals that will receive the situation or substance being tested. So in our chocolate study, this is the group eating chocolate.
- A control group is the opposite of the experimental group: they are not receiving anything in the experiment. So this group would not receive any chocolate.
- Every study has an independent variable – the substance or element being tested, and a dependent variable – the outcome as a result of the application of the independent variable on the experimental group. For our purposes, the chocolate is the independent variable, and the participants’ moods as a result of the chocolate is our dependent variable.
- A blind study means that no one participating in the study knew whether they were in the experimental or control group, so they can’t throw off the study (because let’s face it: when we eat chocolate, we’re convinced life is getting better, right?)
- A double-blind study means that neither the participants in the study, nor the researcher in charge knows which group is the experimental group or the control group. This assures that the researcher’s bias can’t affect the outcome of the study.
- A placebo is often used during drug studies, where one group – the experimental group – receives the drug being tested, and the control group receives what they are told is the drug as well, but is actually a fake pill, often made of sugar. So in our study, we would give the control group something that looked and tasted like chocolate, but really wasn’t (imagine such a thing!)
- A randomized trial means that our “normal, healthy” people were randomly assigned to the experimental and control groups.