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Unformatted text preview: Chapter 9 Testing a difference between the means Research Hypothesis A Research Hypothesis is a statement of an expected or predicted relationship between two or more variables. Testing differences between two Means Memory score of elderly in the treatment and placebo groups: treatment: 81, 82, 83, 82, 80 mean=82 placebo: 76, 78, 77, 79, 75 mean=72 conclusion: treatment group is doing better than placebo group. Testing differences between two Means Memory score of elderly in the treatment and placebo groups: treatment: 90, 98, 63, 74, 85 mean=82 placebo: 70, 90, 91, 56, 78 mean=77 making a conclusion is not easy this time. Required steps in an Experimental Research Asking a scientific question. Having a research hypothesis. Choosing a research design. Subject selection. Creating equivalent groups. Manipulating the independent variable. Measuring the dependent variable. Equivalent groups Equivalent groups are groups in which the subjects are not expected to differ in any systematic way before they receive the independent variable. Random Assignment Random assignment means that any individual selected for the experiment has an equal chance of being in any of the treatment groups. Probability of assignment to each group is equal. The assignment of one subject to a group does not affect the assignment of any other individual to the same group. Independent variable Independent variable  the variable that is manipulated. It is also called a factor. One factor betweensubject design is a research design in which one independent variable is manipulated. Dependent variable depends on the value of the independent variable. Extraneous variables Any other variable other than the independent variable that can affect the dependent variable....
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This note was uploaded on 11/30/2009 for the course HP 400m at USC.
 '07
 Nezami,Borovay

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