While undergoing any clinical trials two main type of experiments used are single blind and double blind. Selection of right trial is important as it can affect the outcome of the experiment.So the selection of right trial is important otherwise there would be errors.
In single blind study the subjects don't know whether they are subject of experiment or control group members. But the tester knows but subject does not know its identity.
In double blind study both the subject and tester does not know their identity and roles, both are not told their identity in the experiment.
According to me the double blind study is more better as it prevents the bias in the experiments and results. It is used to prevent bias due to demand characteristics.
Double blind studies are needed because it eliminates any bias that can arise in the course of testing. If you are conducting a clinical trial for a drug you obviously want it to succeed, and if you know which patients are receiving what treatment then you will be more likely to see positive results in those patients. If we use your example of a new Alzheimer's treatment. If I am conducting the research and I know which patients have the real treatment and which have the placebo, then there is a chance that I am going to report things more positively in the case of the patient receiving the treatment. Not this might not be a conscious decision, but a single blind study still allows for this kind of bias that might skew results. A double blind study makes sure that this will not happen, and will allow for true results that are reflective of the efficacy of the new treatment.
Double blind studies much better than a single blind study, mainly to avoid mental bias. Thinking that drug will make someone better alters the mind to feel like it has actually worked. This is true for both the patient and the clinician. If the clinician is not blind to which drug does what, they may foster bias questions and approaches to the patient hinting to what the drug is supposed to do. If the clinician is not aware of the drugs, like in a double blind study then he/she will follow only one method for all drugs and patients and won't be able to foster biased conversations and questions. This way the patient truly won't know what to expect and can't be mentally biased themselves. This allows for the true effect of the drug to be seen.
Blinding study was introduced to avoid bias in the evaluation of treatment effects. As you have mentioned, double blinding studies require blinding patient, who is unaware of which treatment is given and also blinding the investigator. Thus, it guarantee objective judgement of efficacy and safety outcomes. By doing blind study, symptoms and subjective outcomes are not influenced by knowledge of treatment assignment. This improves the reliability of clinical research results. There are may advantages of double blind because the results are shown accurate however there are disadvantages as well. More often, Double blind study is limited in pharmaceutical industry. Such as lack of adequate demographic controls when study is being done, predictability of the drug's identity and recruitment size. In order for drug to be approved, double blind studies are the standards by FDA. It requires two double blind study showing the drug is superior to placebo and at least equal to a standard other competing drug which indicated the certain condition for which the drug is being test.
Overall, double-blind studies are not meant to increase some sort of significance to the investigator, but is more about collecting good data that is not tainted. In single blind studies, there is chance of bias occluding results, therefore causing data to not be reflective of reality. In a double blind study however, the element of bias is eliminated as even the investigators are not aware of who get's what. In these cases, a third party is brought on in order to facilitate the distribution of drugs. This third party does not allow either of the two groups to know what is what, so as to eliminate the bias. Of course, all of this depends on whether or not this third party organization is also unbiased, but that is something that must be taken as a given. Overall, when a double blind study is done, the data can be seen as more valid and trustworthy when compared to data from a single blind study, for reasons mentioned above.
While I see what you mean when you say that having the investigator know what he is giving the subject has no harm, in actuality the exact opposite can actually be the case. If the investigator knows he is giving the subject the actual product, they may end up unconsciously dropping hints through facial movements, verbal emphasis, etc. and that could skew the results in the end which would hurt the entire study. With a double blind study, the chances for that to happen are much less likely to happen because the investigator has no idea who is getting what, so any bias that could possibly occur flies out the window the in the end, the test gets more dependable results.
My neural engineering professor, Dr. Alvarez always would mention her lab using "double-blind" procedures in her experiments. She always stressed how efficient this method was at eliminating any type of biases between the researchers and their subjects.
A double blind study prevents the subject from knowing the treatment they are getting, while also preventing the researcher from knowing what the treatment the subject is taking.
In the example given on developing an Alzheimer's drug, during the clinical phase it would be more efficient for the experiments to be done using a double blind method. If patient one is given the experimental pill and patients two is given a sugar pill, the investigator may tend to favor the results of the patient who took the experimental pill. However, if the researcher does not know either of the subjects treatments, they can not have any biases, leading to more accurate results.
I believe that double is more important than single blind because there would not be anyone altering the experiment. Neither the person being tested and the tester won't know who is being tested which there won't be any favorites. The experiment outcome will reliable and true because it is a random experiment. There is bias when the tester has the power to decide who will take the product by just judging the participant look, attitude, sex, age, etc. It good to not know because it not going to be the testers fault if the experiment fail/succeed, the reason being is that they just are observing they didn't touch anything.
In a single-blind study or experiment, the subjects don't know if they are the experimental test subjects or members of the control group. But the tester knows. In short, the subjects are not told their identities in the setup.
In the double-blind setup, both the tester and the subjects are blinded: both are not told of the subjects' identities in the setup.
In the triple-blind setup, the supervisor (or supervising committee), the tester and the subjects all are blinded: they are not told of the subjects' identities in the setup.
The use of double-blind or triple-blind setups are useful avoiding demand characteristics and/or the placebo effect. We can have a better randomised, double-blind, placebo-controlled study this way. This is considered to be the superior model of clinical research since it eliminates outcomes that are produced due to placebo effect, as well as observer bias by the experimenter. The fact that the experimenter does not know which group received the placebo or the experimental drug means that the risk of conscious and unconscious observer bias is reduced, making the study more accurate.
I cant really think Why is it needed to use double blind study since I think single blind i.e. only patient blind must work.In double blind both Investigator and patient will not know about the drug and doctor will have to identify who is given what which would lengthen the process of trial and I think if investigator knows it shouldn't affect the outcome of study
For example: If a research group is developing an Alzhimer's drug and they are in clinical phase how would it affect the investigator if he knows that a patient is given placibo or a drug to cure Alzhimer's.
Whats's your point in this and if you think double blind are better and you provide some example.
I think the main benefit of double versus single-blind studies is to further reduce the introduction of both conscious and unconscious bias. Given that an unconscious bias can be introduced into a study at many levels, I believe that blinding wherever applicable, provides the most representative data. Because of that, I consider double-blind studies to generally be more effective, if not significant, to single-blind studies.
In a single blind study, the participants in the clinical trial do not know if they are receiving the placebo or the real treatment. In a double blind study, both the participants and the experimenters do not know which group got the placebo and which got the experimental treatment.
The double blind method is an important part of the scientific method, used to prevent research outcomes from being influenced by the placebo effect or observer bias.
Single Blind study is the one where only the Patient is not aware as to what drug he is getting, while in Double-Blind Study both the investigator as well as the patient is not aware of the drug being the one that is actually being tested or it is the dummy one.
The Double-blind study subjects' results would be altered if the investigator is inclined to one particular drug, so Double-Blind study is preferred over a single-blind study.
Also, I feel it is necessary to have a control group for study to compare with the people using the drug to have a timeline for comparison.
For most cases, single blind studies suffice for removing bias from the study. As the main reason for skewed data would stem from if subjects knew whether or not they had been given a placebo. However, in many cases, researchers performing the study, and analyzing the data do have a preferred outcome of the study, in order to match their hypothesis. Due to this, it is possible for the researchers to even make incorrect conclusions subconsciously. After all, people tend to see what they want to see in most scenarios. For this reason, double blind and eve triple blind studies are beneficial because they remove all possible instances of bias in the research.
In a single blind study, the experimenters are aware of which subjects are receiving the treatment but the participants are not aware. This type of study is useful from preventing participants from altering the behavior to conform to what they think the reserchers expect. In a double blind study, neither the participants nor the experimenters know who is receiving a particular treatment. This procedure is helpful to prevent bias in research results. This study is useful since the participants are unaware of the group they are in and as well as the researchers are unaware of which subjects are receiving the real treatment and they are less likely to reveal accidental subtle clues that might influence the outcomes of the research.
In a clinical trial, the two major models are single blind and double blind trials. Human behavior is influenced by what we know or believe. In research there is a particular risk of expectation influencing findings leading to biased results. Blinding is used to try to eliminate such bias.
In a single blind study, the participants in the clinical trial do not know if they are receiving the placebo or the real treatment. Where as in a double-blind study, both the participants and the experimenters do not know which group got the placebo and which got the experimental treatment.
Blinding patients to the treatment they have received in a controlled trial is very important. Similarly, medical staff caring for patients in a trial should be blinded to treatment allocation to minimize possible bias in patient management and in assessing disease status. For example, the decision to withdraw a patient from a study or to adjust the dose of medication could easily be influenced by knowledge of which treatment group the patient has been assigned to. This makes the study more accurate. . Randomized double blind placebo control studies are considered the “gold standard” in intervention based studies.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3505292/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1118396/
