Question

1. which scenario is best described as an observational study? 1) for a class project, students in health class ask every tenth student entering the school if they eat breakfast in the morning. 2) a researcher wants to learn whether or not there is a link between childrens daily amount of physical activity and their overall energy level. during lunch at the local high school, she distributed a short questionnaire to students in the cafeteria. 3) a social researcher wants to learn whether or not there is a link between attendance and grades. she gathers data from 15 school districts. 4) sixty seniors taking a course in advanced algebra concepts are randomly divided into two classes. one class uses a graphing calculator all the time, and the other class never uses graphing calculators. a guidance counselor wants to determine whether there is a link between graphing calculator use and students final exam grades. justify your response:

Explanation:

An observational study observes subjects without interfering (no treatment/control groups).

• Option 1: Sampling (asking) but still observational? Wait, no—wait, option 3: The researcher gathers existing data (from 15 school districts) without manipulating variables (attendance/grades are already as they are).
• Option 4: Has a treatment (calculator use vs not) → experimental.
• Option 2: Distributing a questionnaire (still observing, but is it experimental? No, but option 3: gathering existing data (no intervention). Wait, let's recheck:
• Observational study: researcher observes without controlling variables.
• Option 3: The social researcher collects data on existing attendance and grades (no manipulation of attendance or grades) → observational.
• Option 1: Asking students (survey, observational? But option 3 is gathering existing data. Wait, maybe I messed up. Wait, let's define:
• Experimental study: has a treatment (assigning groups, manipulating a variable).
• Option 4: Assigns groups (uses calculator vs not) → experimental.
• Option 2: Distributing a questionnaire (still, is she manipulating? No, but is it a survey? But option 3: gathering data from school districts (existing records) → observational (no intervention).
• Option 1: Asking every tenth student (sampling, but is it observational? Yes, but option 3: the researcher is not interfering, just collecting existing data. Wait, maybe the key is: in observational, you don't impose a treatment.
• Option 3: She gathers data from 15 school districts (attendance and grades are already happening; she's just observing the relationship without changing anything).
• Option 1: Asking students (still, no treatment, but is it a survey? But option 3 is more about existing data. Wait, maybe the correct answer is 3? Wait, no—wait, let's check each:

1. Students ask every tenth student (survey, observational, but is it a study? Yes, but 3: gathering data from districts (no intervention).
2. Distributing questionnaire (survey, observational, but is there a treatment? No.
3. Gathering data from districts (no manipulation, just observing existing data) → observational.
4. Divided into two classes (treatment: calculator use) → experimental.

So the best is 3, because in 1 and 2, they are collecting data via survey, but in 3, it's existing data (no interaction with subjects, just collecting records). Wait, maybe the answer is 3. Let's justify: In an observational study, the researcher does not manipulate variables. Option 3: The researcher collects data on attendance and grades from existing school districts (no manipulation of attendance or grades). Options 1 and 2 involve surveys (still observational, but maybe 3 is more "observational" as it's using existing data). Option 4 is experimental (assigns treatment: calculator use). So the best is 3.

Answer:

1. A social researcher wants to learn whether or not there is a link between attendance and grades. She gathers data from 15 school districts.