Please point me in the direction of being able to describe the structure of a "double-blind" experiment.
I went to www.google.com and entered double-blind experiment, and here are the results:
http://www.google.com/search?q=double-blind+experiment&rls=com.microsoft:en-us:IE-SearchBox&ie=UTF-8&oe=UTF-8&sourceid=ie7&rlz=1I7GGIH
I did that - but was lost as to how to describe the structure of well developed double blind study.
It has something to do with how neither the researchers nor the participants are fully aware of the situation.
An independent variable is the potential stimulus or cause, usually directly manipulated by the experimenter, so it could also be called a manipulative variable.
A dependent variable is the response or measure of results.
Extraneous variables — other than the independent variable — potentially can affect the dependent variable, so they must be controlled. If possible, you try to keep them constant between the experimental and control group.
The experimental group receives the independent variable.
The control group is similar to experimental, except it does not receive the independent variable. Extraneous variables are balanced between experimental and control groups.
Types of experiments
1. Single blind gives the control group a placebo — a substance that is inert, it has no physical effect. Subjects don't know if they are in experimental or control group to reduce placebo effect, a change in behavior solely due to believing that you are getting the independent variable.
2. Double blind keeps both subjects and experimenter ignorant of group setup. Distribution of the independent variable and placebo are controlled by third party. This controls for experimenter bias and self-fulfilling prophecy, which means that experimenters with particular expectations are likely to consciously or unconsciously to bias the experiment and influence it to conform to their expectations.
As an example, suppose you want to find out if fluorides reduce dental cavities. You would find two groups, trying to control the extraneous variables. Extraneous variables are found by surveying previous research in the area. In this case, you would match the groups in terms of previous history of cavities, diet and dental hygiene habits including how and how often they brush their teeth.
The experimental group would get toothpaste with the independent variable, the fluoride, while the control group would not have the fluoride in their toothpaste. The toothpaste without the fluoride would be the placebo.
The dependent variable would be the number of cavities after participating in the experiment for a time. The dependent variable indicates the results, but it is not the results. At the end of the experiment, both groups could have no change in cavities or one of the groups could have a greater reduction in cavities. (Of course, if the fluoride increased cavities, you wouldn't want to use it.) All of these varied results would be indicated in terms of the dependent variable.
If only the subjects do not know who is getting the fluoride, it is a single blind experiment. If both the subjects and experimenter do not know, it is a double blind.
I hope this helps a little more. Thanks for asking.
To describe the structure of a "double-blind" experiment, you need to understand its key components and steps. Here's an explanation of a double-blind experiment and how to structure it:
1. Objective: Clearly define the research question or hypothesis that you want to investigate through the experiment. This could involve testing the effectiveness of a new drug, comparing two treatments, or examining the impact of an intervention.
2. Sample Selection: Choose a random and representative sample of participants or subjects who will take part in the experiment. It is important to ensure that the sample is diverse enough to generate reliable and meaningful results.
3. Randomization: Randomly assign participants to either the experimental or control group. Randomization helps to minimize potential biases and ensures that characteristics of participants are evenly distributed.
4. Experimental Group: This group receives the treatment or intervention being tested. For example, it could be a new drug, a specific therapy, or a modified procedure. This group is compared to the control group to evaluate the effectiveness of the treatment being studied.
5. Control Group: This group does not receive the treatment or intervention and serves as a baseline for comparison. The control group is designed to isolate the effects of the treatment being tested and evaluate its impact accurately.
6. Blinding: In a double-blind experiment, both the participants and the researchers are unaware of who belongs to the experimental or control group. This is done to minimize biases that can result from participants or researchers having knowledge of the group assignment.
7. Placebo Group: In some cases, a placebo group is used as a special control group. This group receives a placebo, which is an inactive substance or treatment that resembles the active treatment being studied. This helps to account for the placebo effect where participants experience improved outcomes due to their belief in the treatment rather than its actual effects.
8. Data Collection: Collect data from both the experimental and control groups using reliable methods. This could involve surveys, tests, observations, or measurements depending on the nature of the experiment.
9. Analysis and Results: Analyze the collected data using appropriate statistical methods to determine if any significant differences exist between the experimental and control groups. This analysis helps to draw conclusions and generate meaningful results for further interpretation.
By following these steps and understanding the core principles of a double-blind experiment, you can effectively structure and carry out this type of scientific study. Remember, the key is to ensure that both the participants and the researchers are unaware of the group assignments throughout the experiment.