11/18 Observational v Experimental Studies

What is the difference between an observational study and an experiment?

• Observational studies compare data.

• Experiments involve imposing a treatment.

• Observational studies have subjects and treatments.

Tags

CCSS.HSS.IC.B.3

A park ranger measures the change in height of all trees of a similar species and age over a month. Half of the trees are within a quarter of a mile from a large lake and half are further away. Is this an observational or experimental study?

• observational

• experimental

Tags

CCSS.HSS.IC.B.3

A park ranger plants 10 trees within a quarter of a mile from a large lake and 10 trees of a similar species and age further than half of a mile from the lake. He then measures the growth of all trees over a month. Is this an experimental or observational study?

• observational

• experimental

Tags

CCSS.HSS.IC.B.3

A zoo installs small "caves" in half of the wildcat cages. The caves provide shade and privacy for the animals and are just large enough to hold a wildcat that is lying down. The caretaker at the zoo then compares the sleeping habits of wildcats with "caves" in their cages to the sleeping habits of wildcats without them. Is this an observational or experimental study?

• observational

• experimental

Tags

CCSS.HSS.IC.B.3

A caretaker at a zoo records the sleeping habits of the wildcats at the zoo for a month. Is this an experimental or observational study?

• experimental

• observational

Tags

CCSS.HSS.IC.B.3

A researcher feeds one group of rats high-fat and high-calorie foods like cheesecake, bacon, and pastries. She feeds a second group of rats a normal, nutritious diet. For two weeks, the researcher records how many calories each rat eats daily, as well as how often it goes to its feeding bowl. She compares data from the one group to the data from the other and finds that the rats that eat the nutritious food get hungry less often and eat a smaller number of calories overall. What is the TREATMENT in this experiment?

• food given to the rats

• fatty foods

• nutritious foods

Should this research topic be addressed through an experimental study or an observational study, and why: "Does being a smoker cause people to get colds more often?"

• observational study, increases chances of being unethical

• experimental study, increases chances of being unethical

• experimental study, prevents being unethical

• observational study, prevents being unethical

Tags

CCSS.HSS.IC.B.3

CCSS.HSS.IC.B.5

CCSS.HSS.ID.C.9

To test the effects of breakfast on grades I ask my students if they ate breakfast and then compare the breakfast eaters grades to the non-breakfast eaters.
This is an example of:

• Observational study
• Experiment
• Neither
• Both observational study and experiment

Tags

CCSS.HSS.IC.B.3

To test the effects of eating breakfast on test grades. I randomly select half of my students and feed them breakfast while giving the other half nothing to eat. I then give them all a test and compare the test grades of each group.

Is this an experiment or an observational study?

• Experiment

• Observational study

• Neither

• Both experiment and observational study.

Tags

CCSS.HSS.IC.B.3

CCSS.HSS.IC.B.5

To test the effects of eating breakfast on test grades. I randomly select half of my students and feed them breakfast while giving the other half nothing to eat. I then give them a test and compare the grades of each group.
 
What are the experimental units in this study?

• Students
• Breakfast
• Tests
• Test grades

Tags

CCSS.HSS.IC.B.3