The Double Blind Study

In this article, we're going to learn what a double-blind study is and I'm going to explain some examples of it. Then we're going to go over the limitations of a double-blind study in the case of professional studies and research the impact of many treatments that can only be confirmed after their effect has been verified in a double-blind study.

What is a double-blind study? A double-blind study is an experiment where both researchers and the participants are blind to the crucial aspects of the study such as the hypothesis the expectations or the allocations of subjects to different groups in double-blind clinical trials neither the experimenters nor the participants are aware of who is receiving treatment. So this brings up the question of why would we do a double-blind study.

The main purpose of a double-blind study is to minimize the effects of the experimenter bias in other words the result of the research is less likely to be affected by external factors such as the experimenters verbally or non-verbally communicating their assumptions about the treatment's efficiency. Or maybe the expectations of the participants. Double-blind studies serve as an invaluable scientific method in the pharmaceutical industry specifically in trials where they're regularly used for determining the impact of new medications.

These types of studies are the very foundation of modern evidence-based medicine. They're often referred to as the gold standard for testing medications. They are the most accurate test available. Double-blind studies are known for their application in medicine. Double-blind studies are widely used to validate theories and ideas in many other fields including agriculture, biology, chemistry, engineering, forensics, and even social sciences.

let's go over an example of a double-blind study identifying successful treatments. It is a complex procedure. Let's say that you're a physician and you prescribe a new medication to a patient. After taking the medication the patient reports improvement in their condition. But this doesn't mean that the treatment is effective. In fact, in many cases, patients will see improvements even when they're not taking active medication. And we're going to talk about this later. To properly test the medication, a double-blind study will have to take place in which the experimenter whoever's acting as a physician administers either the medication or a placebo to the participant who is acting as the patient. In this case, only a third party knows whether the medication was real or not. Then the participants' answers about their treatment will be recorded and sent to a third party. Double-blind studies aren't just used for new medication though a double-blind study was used to see if airport security dogs could sniff out one of the most recent viruses that swept the nation.

let's move on to something called the placebo effect. Almost everyone knows what a placebo is but let's review and see how it ties into double-blind studies. So just as a review a placebo is an inactive substance that does not affect the individual who is taking it. It looks just like the real medication that's being tested so that way the participants can't say whether they're receiving the true treatment or not. Sometimes patients will receive medication that is in reality a sugar pill or a salt pill which should have no measurable effects on the variable that is being tested but, in many cases, the placebo effect prevails, and having just a fake pill is enough to change the results or the beliefs of the patient. Next up I want to talk about how to conduct a double-blind study.

Subjects in double-blind studies are typically divided into three different groups: the treatment or the experimental group, the placebo group, and the control group. Participants who are not receiving any treatment are placed in what is called the control group. This group serves as the baseline for determining whether the medication in question has any significant effects. If the control group gets better over time, then this improvement will set a standard against which the other two groups will be compared. People placed in the treatment group are given the actual medication while subjects placed in the placebo group are offered a placebo pill. The participants in the treatment and placebo groups nor the experimenters have the information on who is receiving the real drug. If the experimenters knew it is likely the results could change due to experimenter bias. At the end of the trial, data is collected from all three groups and compared to determine if the treatment had the expected outcome. If subjects in the placebo group are better off than the control group this positive development can be attributed to the participants' belief that the pill works. But if people in the treatment group improve more than those in the placebo one then the results can be attributed to the effect of the medication. Next up I want to talk about some differences or variations of blind studies.

There are several different types of blind studies being used in research such as double-blind comparative studies, single-blind studies, and even triple-blind studies. So in double-blind comparative studies, one group of participants is given a standard drug instead of a placebo. These studies compare the effects of a new medicine with an old one whose impact has already been proven. This kind of study is useful in determining whether a new treatment is more effective than an existing one. There are also single-blind studies. In single-blind studies, only the participants are not informed whether they are receiving the real treatment. Thus, they are the only blind ones in the experiment. The experimenters on the other hand know which participants belong to which group as we mentioned before. The problem with this is the experimenter bias. Next up we have triple-blind studies.

Triple-blind studies are clinical trials in which knowledge about the treatment is hidden not only from the subjects and the experimenters but also from anyone else involved in organizing the study and data analysis. Before we move on to the limitations of double-blind studies, I wanted to share a short story in which I performed a small double-blind study. Over this summer I've been dabbling in hydroponics from growing lettuce to strawberries and I've learned a ton. Some of the strawberries I've been growing are tasty and I wondered if they tasted better than store-bought ones. So what I did is I set up a mini double-blind study where I placed some of my strawberries in a bowl and then some store-bought strawberries in a bowl. Now under each of these bowls, I put a piece of tape with store-bought written on it or homegrown written on it. I had my wife mix up these bowls so even I wouldn't know which one was which. We had some family come over for dinner and I had them select a berry from bowl one and a berry from bowl two and asked them which berry tasted better. The results were in and number two was the winner up until now the patients which were my family and the experimenter which was me did not know which bowl contained which type of strawberries. We were both blind. Now you might be wondering which berries were in bowl two. Fortunately, it was my homegrown strawberries.

One of the limitations is that the types of double-blind studies double blinding is not feasible for all types of trials. For instance, it's not possible to design studies on therapies such as acupuncture, physical therapy, diets, or surgery. In a double-blind manner in these cases, researchers and participants just can't be unaware of who is receiving the therapy. Another limitation is the nocebo effect. Participants in clinical trials must be informed of the possible side effects that may result in an experimental treatment however the mere suggestion of a negative outcome may lead to a negative placebo effect. Also known as the nocebo effect it can result in participant dropouts and the need for additional medications to treat the side effects. In research, the use of a placebo is generally acceptable only in situations where there is no proven acceptable treatment for the condition in question for ethical reasons participants must always be informed of the possibility that they will be given a placebo. As a consequence, some participants may think that they feel the effects of a placebo which makes them believe that they are in the treatment group. The high positive expectancy is a disadvantage that can lead to a misinterpretation of the results. Another downside is the cost of double-blind studies. Double-blind procedures are very expensive. They may take several months to complete and can cost lots of money as experiments often require numerous trials using different groups in order to collect enough data. As a result, double-blind studies can cost up to several million dollars depending on the amount of work required and the industry in which the product is being tested.