Evaluating Statistical Claims

What is the main purpose of using a random sample in a survey?

• To ensure that the sample is small

• To make the results match exactly with the population

• To estimate the population's characteristics without surveying everyone

• To remove all variability from the data.

What is the key difference between an observational study and an experiment?

• Observational studies manipulate variables, experiments do not

• Experiments impose a treatment, observational studies do not

• Both studies always prove causation

• Observational studies use random sampling, experiments do not.

A biased sample is one that...

• Represents the population accurately

• Is too small to be useful

• Has no errors in data collection

• Favors certain outcomes, making results unreliable

A survey finds that 85% of students like a new lunch menu with a ±3% margin of error, what is the confidence interval?

• 80% to 90%

• 82% to 88%

• 78% to 85%

• 85% to 100%

Why do researchers use a control group in experiments?

• To compare results and determine if the treatment caused a change

• To ensure all participants get the treatment

• To introduce bias into the study

• To reduce the sample size

A company tests a new workout plan by surveying only members of their gym. Why might the results be biased?

• Only people interested in fitness are included

• The sample is large enough to be reliable

• The company used random sampling

• The study used a control group.

A researcher records students' study habits and test scores. What type of study is this?

• Experiment

• Survey

• Observational study

• Case study

A local business surveys customers at its store about a new policy. What is a concern?

• The survey is too long

• Only current customers are surveyed

• The sample size is too large

• The survey asks for opinions.

A doctor gives one group a new medicine and another a placebo. What type of study is this?

• Observational study

• Survey

• Case study

• Experiment

A shoe company tests new running shoes on elite marathon athletes. What is a concern?

• The study lacks a control group

• The results may not apply to all runners

• The sample size is too small

• The shoes are tested for too long