Dependent Variables

1
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.

2
Measuring the dependent variable

• Self-report measures Used to measure attitudes,
  liking for someone, judgments about someones
  personality characteristics, intended behaviors,
  emotional states, and many other aspects of human
  thought and behavior. Rating scales with
  descriptive anchors are most commonly used.
•  
•  

3
Example

• I feel I could properly give myself a breast
  self-examination.
•  
• Strongly
  Strongly
• disagree ___ ___ ___ ___ ___ ___ ___ agree

4
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.

5
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.

6
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.

7
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.