Which of the following statements is true? Check all that apply. We can use results from an observational study to test a claim about a population. We can use results from an observational study to establish an association between two variables. When an observational study has a large sample and follows people for many years, we can use the results to establish a cause-and-effect relationship between two variables. When many observational studies together meet specific criteria, the results can provide varying degrees of evidence for a cause-and-effect relationship between two variables, but we should be cautious in interpreting such results. A well-designed experiment is the only legitimate way to establish a cause-and-effect relationship between two variables.

A study which computes the characteristics of a population by studying individuals in a sample, but does not attempt to operate or influence the variables of interest is known as an operational study.

Thus according to the definition the true statements are:-

We can use results from an observational study to test a claim about a population.

We can use results from an observational study to establish an association between two variables.

When many observational studies together meet specific criteria, the results can provide varying degrees of evidence for a cause-and-effect relationship between two variables, but we should be cautious in interpreting such results.

A well-designed experiment is the only legitimate way to establish a cause-and-effect relationship between two variables.