01
Choose one
1 point
A university wants every class year represented and divides its students into first-year, sophomore, junior, and senior groups before randomly selecting students from each group. Which sampling method is being used?
Free Practice Quiz Question List
5. Planning Samples and Experiments Online Quiz Questions
Use this free practice quiz with 20 questions to review 5. Planning Samples and Experiments, test your knowledge, and prepare for your next test or exam.
20 questions
02
Choose one
1 point
In a randomized experiment, what is the primary purpose of randomly assigning participants to treatment groups?
- A
It helps balance characteristics across treatment groups and supports causal conclusions.
- B
It guarantees that the participants represent the entire target population.
- C
It eliminates all random variability from the study.
- D
It ensures that every person in the population has an equal chance of entering the study.
03
Choose one
1 point
A researcher surveys people entering one nearby gym because they are easy to reach, without randomly selecting participants. What conclusion is most justified?
- A
The results establish causation because the researcher measured an outcome.
- B
The results can be generalized if the sample is large enough.
- C
The results usually describe the observed cases, but broad generalization is weak or unjustified.
- D
The results establish causation if the participants volunteered willingly.
04
Choose all
1 point
Which two design features together provide the strongest support for both population generalization and cause-and-effect conclusions? Select all that apply.
- A
Random selection from the target population
- B
A large sample size by itself
- C
Random assignment to treatment conditions
- D
Allowing participants to choose their preferred treatment
05
Choose all
1 point
Which practices can help reduce bias in a survey? Select all that apply.
- A
Use wording that suggests the preferred answer.
- B
Use neutral wording for survey questions.
- C
Recruit only people who choose to respond to an open online poll.
- D
Follow up with people who do not initially respond.
06
True or false
1 point
True or false: Increasing the sample size generally removes systematic bias caused by a flawed sampling design.
- A
True
- B
False
07
True or false
1 point
True or false: If an observational study finds that people who take a supplement have better health outcomes, the study by itself establishes that the supplement caused the improvement.
- A
True
- B
False
08
Written response
1 point
What term describes a variable whose effects cannot be separated from the effects of the explanatory variable in a study?
09
Written response
1 point
An experiment compares a new treatment with both a placebo control and a standard treatment. How many distinct treatment groups are there? Enter the number of groups.
10
Fill in the blank
1 point
If a survey of all city residents uses only landline telephone numbers, residents who use only mobile phones may suffer from . The list or procedure used to identify members of the population is the .
11
Fill in the blank
1 point
In an experiment, determines which treatment a participant receives, whereas determines who enters the sample.
12
Open ended
1 point
Design a brief study to compare a new medication with a placebo. Explain how random assignment, a double-blind procedure, and a control condition would strengthen the study's evidence for a causal effect, and state one ethical requirement.
13
Choose one
1 point
Students who choose to attend tutoring score higher than students who do not. Which explanation best identifies the causal problem with concluding that tutoring caused the higher scores?
- A
The sample has no variability because all students took the same test.
- B
Prior achievement or motivation may be associated with both tutoring participation and test scores.
- C
Random assignment guarantees that tutoring caused the score difference.
- D
Replication would prove that no other explanation is possible.
14
Choose one
1 point
Which procedure best describes systematic sampling?
- A
Select people who are easiest to contact.
- B
Randomly select a separate sample from each subgroup.
- C
Select every kth case from an ordered list after choosing a random starting point.
- D
Select several natural groups and study everyone in them.
15
Choose one
1 point
A school selects 200 students to estimate the proportion of all enrolled students who regularly exercise. Which statement correctly identifies the population and sample?
- A
The population is the 200 selected students; the sample is every enrolled student.
- B
The population is every enrolled student; the sample is the 200 selected students.
- C
The population is the exercise frequency; the sample is every enrolled student.
- D
The population is the enrollment list; the sample is the exercise frequency.
16
Choose one
1 point
A university wants each class year to be represented while preserving random selection. Which sampling method is most appropriate?
- A
Randomly select several classes and survey every student in those classes.
- B
Select every 20th student from an alphabetized enrollment list after a random start.
- C
Divide students by class year and randomly select students from each year.
- D
Survey students who volunteer after seeing an online invitation.
17
True or false
1 point
True or false: Random selection primarily supports generalizing from a sample to a population, whereas random assignment primarily supports cause-and-effect conclusions.
- A
True
- B
False
18
Choose one
1 point
Researchers compare health outcomes of people who choose to take a vitamin supplement with those of people who do not, without assigning anyone to a group. What conclusion is justified?
- A
It is an experiment, and the supplement necessarily causes any observed difference.
- B
It is an observational study, so the association does not by itself establish causation.
- C
It is a simple random sample, so no causal limitation remains.
- D
It is a randomized experiment because participants chose their own behavior.
19
Written response
1 point
A survey about all adults uses only landline telephone numbers, giving people who use only mobile phones little or no chance of being selected. What type of bias is this?
20
Written response
1 point
An observational study finds that people who carry lighters have higher rates of lung disease. According to the example, which variable confounds this relationship?