AP Statistics : AP Statistics
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Example Questions
Example Question #1 : How To Identify Confounding Factors In An Experiment
A study finds that caffeine intake has a strong positive correlation with grades for college students. In other words, on average, the more caffeine intake a student has, the higher a grade the student gets.
Which of the following could potentially be a confounding variable in this experiment?
The amount of soda that each student consumes
Amount of sleep a student gets each night
The caffeine intake of students
The grade a student receives
The amount of coffee that each student drinks
Amount of sleep a student gets each night
The only confounding variable in this experiment is the amount of sleep that each student gets. A confounding variable is one that has an impact on both the dependent and independent variable. It is possible that the amount of sleep a student gets is related to caffeine intake, which in turn affects the grade a student receives on a test or assignment.
Example Question #93 : Data
An experiment testing the effects of caffeine on endurance performance in athletes assigns caffeine to a randomly selected group of athletes and has them exercise. Another trial was conducted in which the same group exercised without anything given to them to take. The results did not match the expected results. What should be done to improve this experiment?
Caffeine may affect different people in different ways, so varying amounts of caffeine should be administered.
A different group should be used for each trial because the athletes' first trial may have influenced their second trial.
Nothing, the experiment is sound
There may a placebo effect with the caffeine, so an identical application without caffeine should be given to the control group.
The group should be randomly selected from a population of athletes and non-athletes, not just athletes.
There may a placebo effect with the caffeine, so an identical application without caffeine should be given to the control group.
The placebo effect can potentially be a confounding variable. By knowingly taking a substance, participants may feel more energenized. By administering the same substance both trials, with the only thing changed being caffeine content, this corrects for this possible confounding variable.
Example Question #1 : How To Identify Confounding Factors In An Experiment
A small local umbrella company is trying to test the effectiveness of their umbrellas by looking at how many umbrellas they sell each year.
In 2014, the company sold 2,000 umbrellas.
In 2015, they sold 1,500 umbrellas.
They assume that their umbrellas are less effective which is why sales decreased.
However, there could be many confounding factors. Which of the following is NOT a possible confounding factor?
There may have been less rain in 2015 than in 2014, therefore decreasing the need for umbrellas.
An increase in prices may have led to decreased sales.
There are no confounding factors.
If the same people live in the city during 2014 and 2015, people may already have umbrellas in 2015 and might not need to buy them.
Three of these could be confounding factors.
Three of these could be confounding factors.
Any of these answers could explain why umbrella sales dropped. You cannot assume any specific cause explains a change in data like this-- further experimentation should be done rather than assuming cause and effect.
Example Question #11 : Data Collection
A study is trying to determine if a particular medication (Y) is effective in weight loss. Patients participating in the study were randomly assigned to groups A, B, C, D, or E. Group A will receive one dose of Y, Group B will receive two doses of Y, Group C will receive three doses of Y, Group D will receive four doses of Y, and Group E will serve as the control group.
Which group will be receiving the placebo (a sugar pill)?
Group E
Group D
Group B
Group C
Group A
Group E
The control group in an experiment typically receives placebo treatments (in this case - Group E). Since all of the other groups are receiving at least one dose of the medication, they are considered to be experimental groups.
Example Question #1 : How To Identify The Placebo Effect In An Experiment
To test if vitamin C actually makes people feel better, a vitamin company decides to run a 5-day study where they give one group of 100 sick participants vitamin C pills and another group of 100 sick people placebo pills, and monitored another group of 100 sick people who took no pills.
At the end of the 5-day experiment, 90 participants in the vitamin C group reported feeling better. 30 participants in the no-pill group felt better after the 5-day period. Interestingly, 50 participants in the placebo group felt better after the 5-day period.
What could explain these numbers?
5 days is too long for the experiment.
The placebo effect: some participants in the placebo group began to feel better because they thought they were taking something that would help them.
Vitamin C actually makes people feel sicker.
5 days is too short for the experiment.
There is no logical explanation.
The placebo effect: some participants in the placebo group began to feel better because they thought they were taking something that would help them.
The placebo effect is when effects are seen in a group of people who did not actually receive a treatment.
In the vitamin C group, 90 participants felt better.
Naturally (no-pill), 30 participants felt better.
With the placebo, 50 participants felt better. Since more people felt better with the placebo than with no treatment at all, it appears that some percentage of people believed that they would feel better with a pill and actually began to feel better due to the placebo effect.
Example Question #1 : How To Establish Blind Experiments
A study is attempting to test various brands of cola against each other. Which of these would not be a measure that could be used to help create a double blind test?
Removing or covering up the labels on the cans or bottles.
Making sure the test administrator also does not know the brand of each sample until after the test.
Randomizing the placement of the cola samples.
Filling the sample cups the same way.
Serving the samples to the taster in their usual containers.
Serving the samples to the taster in their usual containers.
Remember that a double blind experiment means that neither the subject nor the person conducting the experiment knows the identity of the various treatments until the test is over, so as to minimize bias.
Therefore of the options,
serving the samples to the taster in their usual containers, is the one which would not help create a double blind test.
Example Question #1 : How To Establish Blind Experiments
Which of the following is an example of a double blind experiment?
An experiment in which researchers know which therapy test subjects are receiving, but test subjects are unaware
None of these are an example of a double blind experiment
An experiment in which neither the test subjects nor the researchers know who is receiving the treatment and who is receiving the placebo
An experiment in which both test subjects and researchers are aware of who is receiving the treatment and who is receiving the placebo
An experiment in which test subjects know which therapy they are receiving, but researchers are unaware
An experiment in which neither the test subjects nor the researchers know who is receiving the treatment and who is receiving the placebo
A double blind experiment requires that both researchers and test subjects are unaware of who is receiving the treatment and who is receiving the placebo. If only one group is unaware, it is a single blind experiment. If both groups are aware, the experiment is not blinded.
Example Question #2 : How To Establish Blind Experiments
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 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
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 and test subjects are aware of who is receiving a placebo and who is receiving a therapy.
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.
Keep the participant identities hidden from the experimenters permanently.
Blindfold the participants while they take the pills.
Randomly sort people into the Experimental or Placebo groups, without letting them know which pill they received.
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 #301 : Ap Statistics
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 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 all participants the placebo pill and measure nail growth.
This test cannot be done as 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.
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.
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