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Ebook Methods in behavioral research (10th edition): Part 2

(BQ) Part 2 book "Methods in behavioral research" has contents: Complex experimental designs; single case, quasi experimental, and developmental research; understanding research results - description and correlation; generalizing results.and other contents. | www.downloadslide.com 10 Complex Experimental Designs LEARNING OBJECTIVES ■ ■ ■ ■ ■ Define a factorial design and discuss reasons a researcher would use this design. Describe the information provided by main effects and interaction effects in a factorial design. Describe an IV ϫ PV design. Discuss the role of simple main effects in interpreting interactions. Compare the assignment of participants in an independent groups design, a repeated measures design, and a mixed factorial design. 183 www.downloadslide.com hus far we have focused primarily on the simplest experimental design, in which one independent variable is manipulated with two levels and one dependent variable is measured. This simple design allows us to examine important aspects of research, such as internal validity and procedures for assigning participants to conditions. However, researchers often investigate problems that demand more complicated designs. These complex experimental designs are the subject of this chapter. T INCREASING THE NUMBER OF LEVELS OF AN INDEPENDENT VARIABLE FIGURE 10.1 Results of a hypothetical experiment: linear versus positive monotonic functions Performance Level (Percent Correct) In the simplest experimental design, there are only two levels of the independent variable. However, a researcher might want to design an experiment with three or more levels for several reasons. First, a design with only two levels of the independent variable cannot provide very much information about the exact form of the relationship between the independent and dependent variables. For example, Figure 10.1 shows the outcome of a hypothetical experiment on the relationship between motivation and performance on a motor task. The solid line describes the results when there are only two levels—no reward for good performance and $4.00 promised for high performance. Because there are only two levels, the relationship can be described only with a straight line. We do not know what the .