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Dependent Variables When researchers study the relationship between variables, the variables are usually conceptualized as having a cause-and-effect connection. The variable that is the “effect” or is “measured” is the dependent variable.
Measuring the dependent variable Self-report measures: Used to measure attitudes, liking for someone, judgments about someone’s personality characteristics, intended behaviors, emotional states, and many other aspects of human thought and behavior. Rating scales with descriptive anchors are most commonly used.
Example: I feel I could properly give myself a breast self-examination. Strongly Strongly disagree ___ ___ ___ ___ ___ ___ ___ agree
Measuring the dependent variable cont… Behavioral measures: Direct observations of behaviors. Often, the researcher must decide whether to record the number of times a behavior occurs in a given time period – the rate of a behavior; how quickly a response occurs after a stimulus – a reaction time; or how long a behavior lasts – a measure of duration.
Measuring the dependent variable cont… Physiological measures: Recordings of the physiological responses of the body. Examples of such responses include the GSR (galvanic skin response) which measures general emotional arousal and anxiety, the EMG (electromyogram) which measures muscle tension, and the EEG (electroencephalogram) which measures electrical activity of brain cells.
Sensitivity of the dependent variable The dependent variable should be sensitive enough to detect differences between groups. EX: “Do you like this person?” with yes/no response. “How much do you like this person?” on a 5- or 7- point scale.
Sensitivity of the dependent variable cont… The issue of sensitivity is mainly important when measuring human performance. Sometimes a task is so easy that everyone does well regardless of the conditions that are manipulated by the independent variable. This is called a ceiling effect where the independent variable appears to have no effect on the dependent measure because participants quickly reach the maximum performance level. A floor effect is when a task is so difficult that hardly anyone can perform well.