Experimental research is commonly used in sciences such as sociology and psychology, physics, chemistry, biology and medicine etc. Experimental research tests a hypothesis and establishes causation by using independent and dependent variables in a controlled environment. KEY POINTS
Experiments are generally the most precise studies and have the most conclusive power. They are particularly effective in supporting hypotheses about cause and effect relationships. However, since the conditions are artificial, they may not apply to everyday situations. A well designed experiment has features that control random variables to make sure that the effect measured is caused by the independent variable being manipulated. These features include random assignment, use of a control group, and use of a single or double-blind design. An experimenter decides how to manipulate the independent variable, but only measures the dependent variable. In a good experiment, only the independent variable will affect the dependent variable. TERMS
Random assignment of subjects to experimental and control conditions is a process used to evenly distribute the individual qualities of the participants across the conditions. dependent variable
The aspect or subject of an experiment that is influenced by the manipulated aspect; an outcome measured to see the effectiveness of the treatment independent variable
The variable that is changed or manipulated in a series of experiments EXAMPLES
A number of years ago some psychologists hypothesized that fear will cause a person to want to affiliate with other people. In one experiment, subjects were randomly divided into two groups. The experimental group (high fear group) was told that during the experiment they would be getting extremely painful electric shocks. The control group (low fear group) was told that the shock they would receive would be like a soft touch. Both groups were asked if they preferred waiting along or with others who were also going to be shocked. (No one was really shocked! ) All subjects were interviewed by the same experimenter in the same room. When a significantly larger percentage of the experimental group subjects asked to wait with others, the researchers concluded that high fear increases the desire to affiliate with others. In this experiment, the level of fear (defined as being in either the painful or painless shock group) is the independent variable, and choosing to wait alone or with others is the dependent variable.
Experimental research in psychology is the application of the scientific method to achieve the four goals of psychology: describing, explaining, predicting, and controlling behavior and mental processes. A psychologist can use experimental research to test a specific hypothesis by measuring and manipulating variables. By creating a controlled environment, researchers can test the effects of an independent variable on a dependent variable or variables. One of the main strengths of experimental research is that it can determine a cause and effect relationship between two variables. However, because of its reliance on a controlled, artificial environment, this kind of research is often difficult to generalize to real world situations. Independent and Dependent Variables
In an experimental study, the independent variable is the factor that the experimenter controls and manipulates throughout the experiment. The dependent variable, on the other hand, is the variable that is influenced and affected by the independent variable. In a simple experiment, a researcher might hypothesize that cookies will make individuals work harder. In one condition, participants will be offered a cookie if they complete a task, while in another they is not. In this case the presence of a reward (the cookie) is the independent variable and completing the task is the dependent variable. An experiment can have more than one independent...
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