Question

experimental vs. observational
a study took a random sample of students and asked them about their bedtime schedules. the data showed that people who sleep for at least 8 hours before the exam day were more likely to get good grades than those who sleep for less than 8 hours. is this an observational or experimental study?
experimental
observational

Explanation:

In an observational study, researchers observe and record data without interfering or manipulating variables. Here, the study simply asked students about their existing bedtime schedules (no manipulation of sleep hours was done). In an experimental study, there would be an intervention (like assigning students to different sleep - hour groups). Since there was no intervention and just data collection based on existing behaviors, it's observational.

Answer:

observational