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Question
question 8 of 10 which situation is an example of an observational study? a. interviewing college students to find what percentage expect a job immediately after graduation b. calling a sample of registered voters before an election to find out what issues concern them most c. collecting the cholesterol readings of a group of elderly people in a small town d. testing the effectiveness of a new hair product by allowing one group to use it and comparing results against a group that doesnt use it
An observational study involves observing and measuring variables without intervening or manipulating the subjects.
- Option A: Interviewing to find job expectations is a survey, but still observational as no manipulation. However, let's check others.
- Option B: Calling voters to find concerns is a survey, observational. But let's check C and D.
- Option C: Collecting cholesterol readings of elderly people - here, we are just observing their cholesterol levels without any intervention (like giving a treatment or changing their behavior).
- Option D: Testing a hair product by having a group use it and a control group - this is an experiment (with manipulation: giving the product to one group), not observational.
Now, between A, B, C: In an observational study, sometimes we just collect data on existing conditions. Collecting cholesterol readings (C) is observing a health parameter without interfering. Interviews (A, B) are also observational, but C is a clear example of observing a biological parameter without manipulation. Wait, but let's recall: An observational study is when you don't assign treatments. So in C, we are just collecting data on their cholesterol (no treatment given). In A and B, we are asking questions (surveys, which are a type of observational study). But the key is that in D, there's a treatment (using the hair product) vs control. So D is an experiment. Now, among A, B, C: which is the best example? Let's see the definitions. An observational study can be a survey (asking questions) or a study where you observe a population's characteristics. But in C, we are collecting a biological measurement without any intervention. Let's check the options again.
Wait, the question is which is an example of an observational study. Let's recall: Observational study: researchers observe subjects and measure variables of interest without assigning treatments. Experimental study: researchers assign treatments (like in D, assigning the hair product to one group). So:
- A: Interviewing (survey, observational)
- B: Calling voters (survey, observational)
- C: Collecting cholesterol (observational, as no treatment)
- D: Experiment (treatment assigned)
Now, the question is which is an example. All A, B, C are observational? Wait, no, maybe I made a mistake. Wait, in A and B, we are asking people (so it's a survey, which is a type of observational study). In C, we are collecting a physical measurement. But the key is that D is an experiment. So the answer is C? Wait, no, let's check again. Wait, maybe the options: Let's analyze each:
A: Interviewing college students to find job expectations: this is a survey, observational (no manipulation).
B: Calling voters to find concerns: survey, observational.
C: Collecting cholesterol readings of elderly: observational (no manipulation, just measuring existing cholesterol).
D: Testing hair product: experiment (manipulation: giving product to one group).
But the question is which is an example. Wait, maybe the intended answer is C? Or maybe A or B? Wait, no, let's check the definition again. An observational study is when you observe a group without trying to affect them. So in C, you are just collecting their cholesterol (no intervention). In A and B, you are asking questions (still observational, as you aren't changing anything). But maybe the question is looking for the one that's not a survey but a study of a biological parameter. Wait, maybe the answer is C. Wait, but let's check the options again.
Wait, the options:
A: Interviewing (survey)
B: Calling (survey)
C: Collecting cho…
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C. Collecting the cholesterol readings of a group of elderly people in a small town