Unit 1 Section 1-5

1-5: Observational and Experimental Studies  Observational Study - the researcher merely observes what is happening or what has happened in the past and tries to draw conclusions based on these observations.  For Example : Motorcycle owners are getting older and richer.  Data was compared based on income of motorcycle owners over a period of time.

Section 1-5  Experimental Study – the researcher manipulates one of the variables and tries to determine how the manipulation influences other variables.  For Example : Sit-up motivation experiment  Quasi-Experimental Study – when random assignment is not possible, researchers use intact groups. The treatment should be assigned at random.  In either case, the group being manipulated is called the treatment group. The other is called the control group.

Section 1-5  Variables in Studies – usually include one or more independent variables and one dependent variable.  Independent Variable is the one being manipulated by the researcher. It can also be called the explanatory variable.  Dependent Variable is the one that you would like to determine whether it is being affected by the independent variable. It can also be called the outcome variable.

Observational Study  Advantages :  Usually occurs in a natural setting (not a lab).  They can be used when it is unethical or dangerous to conduct an experiment.  They also can be used when the researcher cannot manipulate the variables.  Disadvantages :  Definite cause and effect cannot always be determined because other factors may have led to the results.  They can be expensive and time-consuming.  They also can have unreliable data when relying on recordings from the past. Section 1-5

Experimental Study  Advantages :  Researcher has much more control (over who is in groups and manipulating the independent variable).  Disadvantages :  They may occur in unnatural settings such as labs and special classrooms.  This can lead to the Hawthorne effect  They can also have confounding variables. Section 1-5

 The Hawthorne Effect  This effect was discovered in 1924 in a study of workers at the Hawthorne plant of the Western Electric Company.  Subjects who knew they were participating in an experiment actually changed their behavior. Therefore, the results of the research was affected.  Confounding variables - one that influences the dependent variable but cannot be separated from the independent variable.

 Complete pg. 16  #’s 1 – 6  Read and take notes on Section 1-6 (pg ) Homework