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Essential Features of the Experimental Method


1. Definition of Experiment: a systematic research study in which the investigator directly varies some factor (or factors), holding everything else constant.
 

2. Establishing Independent Variables:
 

a. Definition of independent variable: the factor of interest to the experimenter, the one that is being studied to see if it will influence behavior.

b. Independent variables must have a minimum of two levels. That is, at the very least, an experiment involves a comparison between two situations (or conditions).
 

3. Varieties of Independent Variables

a. Situational variables: different features in the environment that subjects might encounter

b. Task variables: experimenters vary the type of task performed by subjects


4. Control groups = comparison group

5. Controlling extraneous variables

a. EXTRANEOUS VARIABLES: uncontrolled factors that are not of interest to the experimenter.

b. CONFOUNDING VARIABLES: any uncontrolled extraneous variable that is correlated with the independent variable and could provide an alternative explanation of the results.
 

6. Measuring dependent variables

a. DEPENDENT VARIABLE: those behaviors that are the measured outcomes of experiments


7. Manipulated variables versus Subject variables

    The term SUBJECT variables refers to already existing characteristics of the subjects participating in the study, such as:


8. Drawing conclusions using subject variables: