PSY 121 Chapter Notes - Chapter 8: Statistical Hypothesis Testing, Random Assignment, Dependent And Independent Variables
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In the experimental method, the researcher attempts to control all extraneous variables. A confounding variable is a variable that varies along with the independent variable. Confounding occurs when the effects of the independent variable and an uncontrolled variable are intertwined so you cannot determine which of the variables is responsible for the observed effect. Good experimental design requires eliminating possible confounding variables that could result in alternative explanations. A research can claim that the independent variable causes the results only by eliminating competing, alternative explanations. When the results of an experiment can confidently be attributed to the effect of the independent variable, the experiment is said to have internal validity (refers to the ability to draw conclusions about causal relationships from our data) To achieve internal validity, the researcher must design and conduct the experiment so that only the independent variable can be the cause of the results. The simplest possible experimental design has two variables:
