What type of Study? (Aug 11)

A group of researchers records the eating habits of teenagers over a month without interfering in their choices.

• observational study

• experiment

• Survey

Scientists give one group of plants a new fertilizer and another group no fertilizer to compare growth rates.

• Observational Study

• Experiment

• Survey

A company sends out a questionnaire asking customers how satisfied they are with their service.

• Observational Study

• Experiment

• Survey

Doctors monitor patients who already take a certain medication to see if it affects their blood pressure.

• Observational Study

• Experiment

• Survey

A school asks students to fill out a form about their favorite subjects and hobbies.

• Observational Study

• Experiment

• Survey

A psychologist gives one group of participants a new therapy technique and another group the standard method, then compares results.

• Observational Study

• Experiment

• Survey

An ​ (a)   is the group in an experiment where the independent variable is being changed or altered. The ​ (b)   , where the variables are kept unchanged, is used to provide a comparison to the groups being tested.

• experimental group
• control group