1. OBJECTIVE: TO BE ABLE TO EXPLAIN THE DIFFERENCE BETWEEN AN OBSERVATIONAL AND AN EXPERIMENTAL STUDY 1-5: Observational and Experimental Studies

2. What is an observational study? A study in which the researcher observes what is happening or what has happened in the past & tries to draw conclusions based on these observations

3. What is an experimental study? A study in which the researcher manipulates one of the variables & tries to determine how this influences other variables.

4. What is a quasi-experimental study? A study which uses intact groups rather than random assignment of subjects to groups.

5. In an experimental study, what is the independent variable? The variable being manipulated by the researcher It is also called the explanatory variable

6. What is the dependent variable? The resultant variable or outcome variable

7. What is the treatment group? The group in a study that received the special instruction

8. What is the control group? The group in a study that is not given any the special instruction

9. What is the Hawthorne effect? Subjects change behavior when they know they are participating in an experiment

10. What is a confounding variable? One that influences the dependent or outcome variable but cannot be separated from the independent variable.

11. List the advantages and disadvantages of each type of statistical study. AdvantagesDisadvantages Control of subject selection & grouping Control of independent variable Hawthorne effect Unnatural settings results may not apply to natural setting Confounding variable Occurs in natural setting Can be done in situations where it would be unethical or dangerous to do experiment Variable that cannot be manipulated by researcher Since variables are uncontrolled, definite cause-effect cannot be shown Can be expensive and time consuming Inaccurate data Experimental Studies Observational Studies

12. Is it possible to reach conflicting conclusions when two studies on the same subject are conducted? Yes… the butter saga….

13. In the three studies comparing the choice between butter and margarine, why were the results seemingly contradictory? They used different types of margarine, and then changed focus from saturated to trans fats.