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How to What Is a Double Blind Study

we're going to learn what a double-blind study is, and I'm going to explain some examples. 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 can only be confirmed after their effect has been verified in a double-blind study. Let's dig right in. First off, what is a double-blind study?




Well, 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, why would we do a double-blind study? Well, the main purpose of a double-blind study is to minimize the effects of the experimenter bias. In other words, the results of the research are less likely to be affected by external factors, such as the experimenters verbally or nonverbally 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 are 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. That is, the most accurate test available. While 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.


Next, let's go over an example of a double-blind study. Identifying successful treatments 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 actually 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 is 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 participant's answers about their treatment will be recorded and sent to a third party.


Double-blind studies aren't just used for a new medication, though. A double-blind study was actually 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 has no effect on 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 actually 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 and 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 actually receiving the real drug.


If the experimenters knew, it is likely the results could change due to experimenter bias, which we recently posted a video about. Anyways, 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 participant's belief that the pill works. But if people in the treatment group improved 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 TripleBlind 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.


TripleBlind 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 personally 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 really 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 storebought 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 a dinner, and I had them select a berry from bowl one and a berry from bowl two and ask 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, and you might be wondering which berries were in the bowl too. Fortunately, it was my homegrown strawberries. Now, this video is sponsored by Skillshare, but I've actually had a Skillshare account for almost five years now, and I'm always impressed at the quality of education I find there. Every week new classes are being added, but one that I highly recommend watching is Growing Hydroponic Lettuce by Caleb Johnson. This class is actually the one that helped me a ton in learning about the PH of my nutrient solution and learning how to germinate my own seeds.


If you don't know about Skillshare by now, they're an online learning platform with over 17,000 classes at the moment and there are no Ads. If you're interested, the first 1000 people to use my link in the description below will actually get a one-month free trial of Skillshare. You can use the link or you can use my code Practical Psychology at checkout. Let's go back to the limitations of double-blind studies. Despite their significance, double-blind studies hold several limitations and do not apply to every type of research.


The first one is the number of participants. To be effective, a double-blind study must include at least 100 participants and preferably as many as 300. Although effective treatments can also be proven in some small-scale trials, many double-blind studies are too limited in their size to provide a representative sample and establish meaningful patterns. Studies involving fewer than 30 participants generally can't provide proof of a theory. Another limitation is 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 treatment. Another limitation is the nocebo effect. Now, 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 arecosare costly and may take several months to complete and lots of money as experiments often require numerous trials using different groups 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.


Wrapping this video up. I want to thank you for watching. I really hope you enjoyed the video and most of all, I hope you learned something today. Another thank you to Skillshare and a quick reminder not to forget to check out Skillshare. If you haven't already, the first 1000 people to click the link in the description below will get a one-month free trial of Skillshare where you can check out all of their interesting and amazing classes.