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Unformatted text preview: Chapter 9 Experimental Research (Reminder: Don’t forget to utilize the concept maps and study questions as you study this and the other chapters.) In this chapter we talk about what experiments are, we talk about how to control for extraneous variables, and we talk about two sets of experimental designs (weak designs and strong designs). (Note: In the next chapter we will talk about middle of the road experimental designs; they are better than the weak designs discussed in this chapter, and they are not as good as the strong designs discussed in this chapter. The middle of the road, or medium quality designs are called quasi-experimental designs.) It is important for you to remember that whenever an experimental research study is conducted the researcher's interest is always in determining cause and effect . • The causal variable is the independent variable (IV) and the effect or outcome variable is the dependent variable (DV). • Experimental research allows us to identify causal relationships because we observe the result of systematically changing one or more variables under controlled conditions. This process is called manipulation. The Experiment Here is our definition of an experiment : The experiment is a situation in which a researcher objectively observes phenomena which are made to occur in a strictly controlled situation where one or more variables are varied and the others are kept constant . • This means that we observe a person's response to a set of conditions that the experimenter presents. • The observations are made in an environment in which all conditions other than the ones the researcher presents are kept constant or controlled. • The conditions which the researcher presents are systematically varied to see if a person's responses change with the variation in these conditions. Independent Variable Manipulation The independent variable is the variable that is assumed to be the cause of the effect. It is the variable that the researcher varies or manipulates in a specific way in order to learn its impact on the outcome variable. Ways of Manipulating the Independent Variable In Figure 9.1 (on page 266) you can see three different ways to manipulate the independent variable. Here is that figure reproduced for your convenience: • First, the independent variable can be manipulated by presenting a condition or treatment to one group of individuals and withholding the condition or treatment from another group of individuals. This is the presence or absence technique . • Second, the independent variable can be manipulated by varying the amount of a condition or variable such as varying the amount of a drug which is given to children with a learning disorder. This is the amount technique ....
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This note was uploaded on 07/26/2011 for the course EDE 4942 taught by Professor Staff during the Spring '11 term at University of Florida.
- Spring '11