5. A team of scientists is testing a new drug on AIDS patients. They expect patients to develop fewer AIDS-related illnesses when given the drug, but they don't expect the drug to cure AIDS.

Thought Process:
a. What is the independent variable?
New drug treatment

b. What is the dependent variable?
Fewer AIDS-related illnesses

c. What control treatment should be used?
The same amount of the drug administered

d. Name a variable that should be controlled.
New drug

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.

Sorry that I didn't respond to your answers.

a. What is the independent variable?
New drug treatment
RIGHT

b. What is the dependent variable?
Fewer AIDS-related illnesses
NOT JUST "FEWER"

c. What control treatment should be used?
The same amount of the drug administered
SEE SINGLE BLIND

d. Name a variable that should be controlled.
New drug
SEE DOUBLE BLIND

d. Name a variable that should be controlled.

The dosage of the drug should be controlled to ensure consistency and accuracy in the results.

d. In this experiment, the variable that should be controlled is the control group. The control group should receive a placebo or a standard treatment that does not contain the new drug. This allows the scientists to compare the effectiveness of the new drug treatment to the control group and determine if the new drug is indeed responsible for the observed reduction in AIDS-related illnesses. By controlling for variables such as the dosage and administration of the drug, the scientists can ensure that any differences observed between the new drug group and the control group are due to the effects of the new drug and not other factors.