What is a Double Blind Study? (Definition + Examples)

in this video 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 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 hypo hthis 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 a 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 experiment or bias in other words the results of the research are 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 that is the most accurate test available while double blind studies are known for the application in medicine double blind studies are widely used to validate theories and ideas and 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 in order to properly test the medication a double blind study will have to take place in which the experimentor 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 participants answer about their treatment will be recorded and sent to the third party double blind studies aren't just used for 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 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 actually receiving the real drug if the experimenters knew it is likely the results could change due to experiment bias of 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 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 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 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 experiment or 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 personally perform formed 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 place 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 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 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 5 years now and I'm always impressed at the quality of Education I find on there every week There's new classes 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 177,000 classes at the moment and there are no ads if you're interested the first 1,000 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 a number of limitations and are not applicable 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 therapy 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 nobo 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 nobo 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 iCal 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 lots of money as experiments often require numerous trials using different groups groups in order to collect enough data as a result double blind studies can cost up to several million dollar 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 learn 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 1,000 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 I'll see in the next 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