AP Statistics Chapter 4 Quiz

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Questions and Answers

A new headache remedy was given to a group of 25 subjects who had headaches. Four hours after taking the new remedy, 20 of the subjects reported that their headaches had disappeared. From this information you conclude:

that the remedy is not effective for the treatment of headaches.

that the new treatment is better than aspirin.

nothing, because there is no control group for comparison. (correct)

that the remedy is effective for the treatment of headaches.

nothing, because the sample size is too small.

There are ten departments at SMART University. To conduct a survey, a researcher selects ten faculty members randomly from each department. The sample selected in this way is called a:

Simple random sample.

Multistage sample.

Systematic sample.

Stratified random sample. (correct)

Voluntary response sample.

There are two statistics classes. The first has 350 students and the second has 250 students. The histogram of $p$ values for the first class should be:

more biased since it is based on a smaller number of tosses.

less variable since it is based on a larger number of students.

more variable since it is based on a smaller number of tosses. (correct)

less biased since it is based on a larger number of students.

A polling agency took a random sample of 1000 likely voters in Florida and another random sample of 1000 likely voters in New Mexico. Other things being equal, the sample from Florida would tend to be ___________ as the sample from New Mexico.

as accurate Signup and view all the answers

A maple sugar manufacturer wants to estimate the average trunk diameter of Sugar Maple trees in a large forest. He divides the forest into several hundred plots and selects 25 at random. This is an example of a:

cluster sample. Signup and view all the answers

A researcher for a consumer products company is testing a new laundry detergent. He randomly assigns families to use either the new formula or the current one. The reason for this random assignment is:

randomization creates similar groups for comparison. Signup and view all the answers

To test the effect of music on productivity, a group of assembly line workers are given music players for one month then work without. This is:

a matched pairs experiment. Signup and view all the answers

A simple random sample of 25 cars was taken in Mechanicsville. Which statement is correct?

A different team would likely obtain a different sample proportion. Signup and view all the answers

A nutritionist wants to study the effect of storage time on vitamin C in freeze dried fruit. The treatment, experimental unit, and response are respectively:

A specific storage time, a fruit pack, amount of vitamin C. Signup and view all the answers

A researcher observes that cities with Major League Baseball teams have more divorces than those without. The most plausible explanation is:

The association is due to a lurking variable. Signup and view all the answers

Control groups are used in experiments to accomplish which one of the following?

Control the effects of outside variables on the outcome. Signup and view all the answers

A survey of recent graduates intends to compare starting salaries of women and men. The best conclusion that can be drawn is:

Whether there is an association between sex and starting salary among graduates. Signup and view all the answers

In an experiment measuring fluoride varnish effect on cavities, what is the major problem?

Subjects were not randomly selected. Signup and view all the answers

The following numbers appear in a table of random digits: 38683 50279 38224 09844 13578 28251 12708 24684. A scientist is to measure total leaf litter in a random sample from a population of 45 sites. What is the correct sample?

Her sample is 38, 35, 02, 22, 40. Signup and view all the answers

To test the effects of a new fertilizer, 100 plots were divided in half. Fertilizer A is applied to one half and B to the other. This is:

a matched pairs experiment. Signup and view all the answers

An airline assessing customer satisfaction randomly samples 10 flights in a month and surveys all passengers. This is an example of a:

cluster sample. Signup and view all the answers

You work for an advertising agency preparing a new television commercial for women. You believe there are differences between employed and non-employed women. Because of these differences, you should use:

a block design. Signup and view all the answers

According to the 1990 census, states with above-average high school dropouts tend to have an above-average number of infant deaths. The most plausible explanation is:

Other variables may be confounded with variable X. Signup and view all the answers

Eighty volunteers using a certain allergy medication are randomly assigned to continue their current medication or switch to a new one. The best conclusion is:

We can determine whether the new drug reduces symptoms more than the old drug for the subjects in the study. Signup and view all the answers

Study Notes

Experimentation and Sampling

A control group is essential to manage external variable effects on outcomes.
Stratified random sampling involves selecting a random sample from different subgroups of a population to ensure representation.
Cluster sampling divides a population into groups (clusters) and randomly selects entire groups for analysis.

Statistical Validity

Sample size impacts variability; smaller samples can yield more variable results.
Randomization in studies helps create similar groups, allowing for fair comparisons of treatments and reducing confounding variables.
Observational studies cannot establish causation, only associations.

Study Design Types

Matched pairs experiments use subjects matched in pairs based on certain characteristics, with each pair receiving different treatments.
Block designs account for variations within sample groups by applying treatments according to specific characteristics (e.g., employment status in commercial testing).

Observational Data and Associative Conclusions

Positive associations between variables do not imply causation; they may result from lurking variables or coincidental correlation.
Different research methodologies may yield various understandings of the same data—results can be affected by sample selection techniques, time, and context.

Sample Representation and Variability

Random samples drawn from large populations can tend to maintain consistent accuracy across demographics.
Independent sampling may yield slightly different proportions, demonstrating variability inherent in statistical sampling.

Treatment Comparisons

In clinical trials, a clear distinction between different treatments allows for meaningful conclusions about efficacy.
Results derived from studies with insufficient attention to factors like the placebo effect may not accurately reflect true treatment impact.

Summary of Findings

Studies involving head-to-head comparisons of products or interventions must address potential biases and inaccuracies to determine genuine effectiveness.
When analyzing survey results, associations found within specific groups may not hold across broader populations or different demographics.

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Description

Test your knowledge with multiple choice questions on Chapter 4 of AP Statistics. This quiz covers key concepts and methods related to experimental design and statistical inference. Perfect for reinforcing your understanding before the exam!