Describe the basic structure of a research experiment. Include the definition and purpose of the hypothesis, independent variable, dependent variable, control group, experimental group, and random assignment

Question

What will be an ideal response?

Answer 1

ANSWER:
A researcher begins designing an experiment with a hypothesis, which can be viewed as a highly educated guess based on systematic observations, a review of previous research, or a scientific theory. A hypothesis takes this form: “If I do this, that will happen.” To test the hypothesis, the researcher manipulates or modifies one or more variables and observes changes in others. The variable controlled and manipulated by an experimenter (“If I do this . . . .”) is known as the independent variable. We need some way to evaluate the effects of this manipulation. We use a dependent variable, defined as the observed result of the manipulation of the independent variable, to tell us “that will happen” as a result of the independent variable. Like the independent variable, our choice of dependent variable is based on our original hypothesis.

In most experiments, we want to know how simply going through the procedures of being in an experiment influences our dependent variable. Perhaps the hassle of going to a laboratory and filling out paperwork changes our behavior. To evaluate these effects, we assign some of our participants to a control group, or a group that experiences all experimental procedures with the exception of exposure to the independent variable. The experience of the control group should be as similar as possible to that of the experimental groups, who do experience the independent variable.

We want to ensure that our dependent variables reflect the outcomes of our independent variables, instead of individual differences among the participants’ personalities, abilities, motivations, and other similar factors. To prevent these individual differences from masking or distorting the effects of our independent variable, we randomly assign participants to experimental or control groups. Random assignment means that each participant has an equal chance of being assigned to any group in an experiment. With random assignment, any differences we see between the behavior of one group and that of another is unlikely to be the result of the individual differences among the participants, which tend to cancel each other out.