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Learn the difference between experimental and correlational research methods, including variables, operational definitions, control groups, confounding variables, and data analysis. Discover how each method helps determine causal relationships and predict outcomes.
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AP Psych Fall 2018 Final Exam FRQ Review Experimental Research Method Versus Correlational Research Methods
Experimental Method • Experiments are carefully controlled experiments that can show a causal relationship between variables • Contains an independent variable and a dependent variable
Experimental Method • Hypothesis = expressing a relationship between 2 variables: • Independent variable = the variable being manipulated to try to cause a change • Dependent variable = depends on the independent variable • A change in the independent variable will produce a change in the dependent variable
Example • The hypothesis (expression of a relationship between two variables) that playing violent video games makes people more likely to have a positive attitude toward real-life violence • What is the independent variable? • What is the dependent variable?
Independent variable = playing violent video games (the hypothesis suggests that a change in playing violent video games will result in a change in attitude). • Dependent variable = the attitude toward violence (depends on playing violent video games)
Operational Definitions of Variables • How are you measuring the variables? • Example: What video games are considered violent? What attitudes are considered positive toward / favoring violence?
Experimental Method: Controlling for Confounding Variables • Confounding variable = any difference other than the independent variable that may affect the dependent variable • Divide into experimental and control groups (assign participants to conditions) to control for confounding variables
Experimental v. Control Group • Experimental group = the one that receives the treatment from the independent variable • Control group = does not get any of the independent variable • Example: experimental group = plays violent video games; control group = does not play violent video games
Correlational Studies • Investigate the same variables as experimental studies, but do not use the terminology independent and dependent variable because do not reveal cause-effect relationships
Correlational Studies • Do not divide participants into separate groups based on the independent variable • Most commonly use surveys to obtain data • Easier, but cannot control for confounding variables like in an experimental study
Correlational Studies • Can only predict the relationship between two variables! • Cannot attribute causation! • Ex. cannot say that playing violent video games causes people to have positive attitudes toward violence
Correlational Studies and Predictions • Positive correlation = one variable increases as other variable increases (positive correlation) • Negative correlation = one variable decreases as other increases • No relationship between variables = zero / no correlation
Experimental Studies and Cause • An experimental study can state that the independent variable causes dependent variable to change…ex playing violent games causes more positive attitudes about violence