PSYC 217 Chapter Notes - Chapter 8: Internal Validity, Confounding, Random Assignment
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Learning objectives: describe how confounding variables affect the internal validity of an experiment. A critical advantages of experiments over non-experiments is that researchers can interpret results in terms of causality altering one variable causes another to change. Manipulating the variable to create groups that differ in the levels of that variable and then comparing those to the levels in the dependent variables. All other variables are constant and if the scores vary then the researcher can conclude that the independent variable caused these changes. Remember that the confounding variable varies along with the independent variable. Anticipating these variables isn"t easy but good experimental design allows researchers to make casual claims because alternative variables are eliminated. When the results of an experiment can be attributed to the independent variable it has internal validity. The simplest experimental design has two variables: the independent variable, experimental group, control group, dependent variable:
