Chapter 7 - Chapter 7: Experimental Research I....

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I. Introduction A. The attribution of causation pervades everyday, common-sense explanations of behavior. B. Many researchers are interested in finding the cause(s) of events and behavior. 1. Just as criminal detective looks for the culprits who committed a crime, researchers interested in attributing causation look for the variable(s) that is responsible for an outcome. a. Recall that the variable thought to produce the outcome is called the independent variable ; and the outcome variable is called the dependent variable . 2. By conducting experiments , researchers assess causal effects of independent variables on dependent variables. a. These systematic investigations are performed under tightly controlled conditions where people are exposed to only the independent variable and the effects of that exposure on the dependent variable are observed. II. Establishing Causation A. It should be pointed out, right at the beginning, that many scholars question the application of principles of causality to explain human behavior, including communication behavior. 1. One distinction that is helpful to the preceding debate is between universal laws and statistical laws . a. Universal laws: Advance explanations that some event or outcome is always preceded by a particular event or “trigger.” b. Statistical laws: Suggest that some event or outcome will be followed a some of the time (along a continuum of high-to-low probability) by a particular event or “trigger.” 2. Based in part on Mill’s reasoning, there are at least three requirements necessary for attributing a causal relationship between an independent and a dependent variable. a. The independent variable must precede the dependent variable. i. Mistakenly believing something that is chronologically impossible is called an anachronism . ii. In experimental research, making sure that the independent variable precedes the dependent variable is accomplished by first exposing research participants to the independent variable and then seeing how that exposure affects the dependent variable. iii. A placebo group believes they are receiving the independent variable being studied, but they are not; placebo means “I shall please” and any change that occurs is then called a placebo effect . b. The independent and dependent variables must covary, that is they must go together in a meaningful way. i. There are many behaviors and events that go together statistically, but are not related in any meaningful manner. These are called spurious relationships or nonsense correlations. c. The changes observed in the dependent variable must be the result of changes in the independent variable an not some other variable. i. If some other variable causes the observed changes, there is an
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This note was uploaded on 04/09/2008 for the course COMM 250 taught by Professor Z during the Spring '08 term at George Mason.

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Chapter 7 - Chapter 7: Experimental Research I....

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