AP Statistics : How to conduct an experiment
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Example Questions
Example Question #302 : Ap Statistics
Which of the following is an example of a single-blind experiment?
An experiment in which the researchers and test subjects are unaware of who is receiving a placebo and who is receiving a therapy.
An experiment in which the researchers and test subjects are aware of who is receiving a placebo and who is receiving a therapy.
An experiment in which the test subjects are aware of who is receiving a placebo and who is receiving a therapy, but the researchers are unaware.
Two of the answers are correct
An experiment in which the researchers are aware of who is receiving a placebo and who is receiving a therapy, but the test subjects are unaware.
Two of the answers are correct
In a single-blind experiment, one group (either the researchers or the test subjects) must be blinded while the other group is aware of who is receiving a placebo and who is receiving a therapy.
The following two examples are correct:
-An experiment in which the test subjects are aware of who is receiving a placebo and who is receiving a therapy, but the researchers are unaware.
-An experiment in which the researchers are aware of who is receiving a placebo and who is receiving a therapy, but the test subjects are unaware.
Example Question #1 : How To Establish Blind Experiments
Alpha Corporation developed a new pill to treat elevated glucose levels. They want to test the efficiency of the pill to lower glucose levels by gathering a sample of people with high glucose and giving them either:
1) A daily dose of their new pill ("Experimental Group")
2) A daily placebo pill that looks the same but does not do anything ("Placebo Group")
How can they make this a "Blind Study"?
Give all participants both pills.
Give the pill to people with high blood glucose and low blood glucose.
Randomly sort people into the Experimental or Placebo groups, without letting them know which pill they received.
Blindfold the participants while they take the pills.
Keep the participant identities hidden from the experimenters permanently.
Randomly sort people into the Experimental or Placebo groups, without letting them know which pill they received.
A blind experiment is one in which the participant does not know which experimental group they are in-- which is accomplished by not letting them know if they are in the Experimental or Placebo group.
Example Question #2 : How To Establish Blind Experiments
A drug company wants to test a new pill that should make people's nails grow twice as quickly as normal. How can they make the study a blind study?
Give half participants the placebo pill and tell them they had the actual pill, and give the rest the actual pill but tell them they have the placebo pill.
This test cannot be done as a blind study.
Give all participants the placebo pill and measure nail growth.
Give all participants the actual pill and measure nail growth.
Give one group of people the actual pill and one group a placebo, but don't tell the participants which pill they are receiving.
Give one group of people the actual pill and one group a placebo, but don't tell the participants which pill they are receiving.
In order for a study to be "blind," the participants can't know which group they are sorted into. For a study to be double-blind, which is even better, the researchers should also be blind to which group participants are in until the study is completed.
Example Question #1 : How To Conduct Matched Pairs Experiments
An company wants to test how much a fuel additive improves the fuel efficiency of cars and has 
Chi-square test of association
Matched pairs 
Two-sample 
One-sample proportion 
Two-sample 
Matched pairs
A matched pairs design t test is the best choice because it will compare the effectiveness of the fuel additive by looking at the means differences of two sample sets where the only variable that is changed from one test to the other test is the introduction of the fuel additive. It makes no sense to compare the performance of, for example, a Ford Mustang with the additive against a Toyota Prius hybrid without the additive. It becomes crucial to compare fuel efficiency with and without the fuel additive for each car.
Example Question #1 : How To Conduct Matched Pairs Experiments
For which of these experiments would a matched pairs design not be ideal?
Comparing effectiveness of two coaches and their methods.
Comparing strength of right arms against strength of left arms.
Evaluating effectiveness of a test preparation regimen.
Evaluating the effectiveness of a diet.
Evaluating effectiveness of a new type of oil filter in various cars.
Comparing effectiveness of two coaches and their methods.
Remember that a matched pairs design tends to involve "before and after" or "with and without" or "left and right" using the same experimental units.
Therefore comparing effectiveness of two coaches and their methods would not be an experiment for the matched pairs design.
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