Formal Experiments

1. Formal Experiments Formal Experiment: Research method that allows the researcher to manipulate the independent variable to study its effect on the defendant variable. [cause-and-effect relationship] Independent Variable: variable whose quantitative value is independently controlled by the researcher. Dependent Variable: variable whose quantitative value is expected to depend on the effects of the independent variable. Formal experiments ---reach conclusions about cause and effect relationships between variables. Formal experiments ---reach conclusions about cause and effect relationships between variables.

2. What's a variable? Answer: A variable is an object, event, idea, feeling, time period, or any other type of category you are trying to measure. There are two types of variables-independent and dependent. (Independent variable) causes a change in (Dependent Variable) and it isn't possible that (Dependent Variable) could cause a change in (Independent Variable).

3. Formal Experiments Independent Variable: is the media (violent or nonviolent). The researcher has independent control over it---in this example, the researcher can choose which participants are shown each media. Dependent Variable: the amount of aggression engaged by children/adolescents. Its quantitative value could depend on which condition the participant is in. One group is placed in the condition that is hypothesized to influence the behavior of the participants (watches the violent movie, in this case)---experimental group. A second group receives none of the supposedly �active� condition of the independent variable (watches a non-violent movie)---control group.

4. Formal Experiments If the behavior of the participants in the experimental group differs from the behavior of the participants in the control group, the hypothesis that differences in the independent variable cause differences in the dependent variable is supported, but under two circumstances: Formal experiments are valid only when the participates are randomly assigned to the experimental or the control group. Formal experiments are valid only if all alternative explanations for the findings have been ruled out through strict experimental control. If boys were shown a violent movie and girls were shown a nonviolent movie, the researcher could not know if any differences in the behavior of the participants in the two groups were due to the violence in the movie or the sex of the participants. Thus, formal experiments require random assignment to experimental conditions to roughly equalize the groups on all factors except the independent variable 2. If half the participants were shown no movie at and the other half had been shown a violent movie, the unlikely possibility that watching any type of film causes an increased aggression could not be ruled out. If boys were shown a violent movie and girls were shown a nonviolent movie, the researcher could not know if any differences in the behavior of the participants in the two groups were due to the violence in the movie or the sex of the participants. Thus, formal experiments require random assignment to experimental conditions to roughly equalize the groups on all factors except the independent variable 2. If half the participants were shown no movie at and the other half had been shown a violent movie, the unlikely possibility that watching any type of film causes an increased aggression could not be ruled out.