AP Statistics Flashcards: Introduction to Planning a Study
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 19 cards to help you master important concepts.
A researcher tracks the diet and health of 1,000 people for 10 years without intervention. What type of study is this?
This is an observational study because the researcher is only observing subjects without imposing any treatments.
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A researcher tracks the diet and health of 1,000 people for 10 years without intervention. What type of study is this?
This is an observational study because the researcher is only observing subjects without imposing any treatments.
What is the key difference between an observational study and an experiment?
The key difference is that treatments are imposed by investigators in an experiment, whereas they are not in an observational study.
Define an experiment.
In an experiment, investigators assign different conditions, known as treatments, to experimental units to observe the effects.
What kind of conclusion can be appropriately drawn from an observational study?
An observational study can identify associations or correlations between variables, but it cannot determine a cause-and-effect relationship.
Why is random selection of a sample important?
Random selection helps ensure the sample is representative of the population, which allows for the results to be generalized.
Under what condition can findings from a sample be generalized to a population?
Generalizations about a population can only be made if the sample was randomly selected or is otherwise representative of that population.
A study of randomly selected American adults finds that those who floss regularly have fewer cavities. Can we conclude flossing *causes* fewer cavities from this study?
No, because this is an observational study, we cannot determine a causal relationship. Other health habits might be the true cause.
What is the scope of generalization for a sample?
A sample is only generalizable to the specific population from which it was selected.
What are the two main types of studies discussed?
The two main types of studies are observational studies and experiments.
Define an observational study.
In an observational study, investigators observe subjects and measure variables of interest, but do not impose treatments.
What is a population in a statistical study?
A population consists of all items or subjects of interest for a study.
If a study's goal is to prove that a new medication causes a reduction in blood pressure, what type of study must be used?
An experiment must be used, as only an experiment with imposed treatments can be used to determine a causal relationship.
What is a sample in a statistical study?
A sample is a subset of the population from which data is collected.
A political pollster randomly selects 1,200 voters from California to gauge support for a state ballot measure. Can these results be generalized to the entire U.S. voting population?
No, the results are only generalizable to the population from which the sample was selected, which is voters in California.
A school administrator reviews student test scores to see if there's a link between attendance and performance. What kind of study is this and can it prove causation?
This is an observational study. It cannot prove that better attendance causes higher performance.
What are 'treatments' in an experiment?
Treatments are the different conditions that are assigned to the experimental units by the investigators.
What is the primary limitation of an observational study regarding cause-and-effect?
Causal relationships between variables cannot be determined from an observational study.
What is the purpose of assigning treatments to experimental units in an experiment?
The purpose is to determine if the different conditions (treatments) cause a change in the observed outcome.
To test a new teaching method, a teacher uses it on one of her two algebra classes and a traditional method on the other. What type of study is this?
This is an experiment because a treatment (the new teaching method) was assigned to one of the experimental units (the classes).