Question

a random sample of 1,000 adults complete a survey about nightly sleeping habits and self - reported levels of stress. results of the survey reveal that adults who sleep more hours per night tend to report lower levels of stress compared to adults who sleep fewer hours per night. given the details of this study, along with what we know about generalization and causation, which one of the following statements is correct?

because random sampling was used, the results of the study can be generalized to the 1,000 adults in the sample, but we cannot infer that stress level is caused by amount of sleep.

the absence of random assignment means we should not generalize the results to the population, nor should we infer that one variable is causing the other.

because the researchers are relying on self - reported stress levels and no random assignment is being used, the results cannot be generalized to the population of adults, nor can we infer that stress level is caused by amount of sleep.

as long as the association between amount of sleep and stress level is statistically significant, we can infer, no matter what sampling method is used, that stress level is caused by amount of sleep.

because random sampling was used in the absence of using random assignment, the results can be generalized to the population of adults, but we cannot infer that stress level is caused by amount of sleep.

Explanation:

Random sampling allows generalization to the population from which the sample is drawn. However, without random - assignment (as in an experiment), we cannot infer causation. Self - reported stress levels may have biases but random sampling is the key factor for generalization here.

Answer:

E. Because random sampling was used in the absence of using random assignment, the results can be generalized to the population of adults, but we cannot infer that stress level is caused by amount of sleep.