Validity and variable in experiment

• Variables


  Characteristics of an organism, environment or experimental situation that vary from one organism to another
• Dependent variables


  Those that are observed to change in response to the independent variables
• Independent variables


  Those that are deliberately manipulated to produce a change in the dependent variables
• Types of Variable Manipulation

  • Instructional Manipulations
  • Events Manipulation
  • Variable manipulation
  • Individual Differences Manipulation
• Operational definition

  Defining Variables Scientifically
• Instruction Manipulation


  1. One group receive one instruction and the other different instruction

  2. Drawback: Participants not attentive

  3. Drawback: Different meaning to different participants
• Events Manipulation


  Altering events that respondents experience (e.g. cold and hot room)
• Variable manipulation

  1. Presence vs Absence: One group receive treatment, one group does not

  2. Amount of Variable: Administer different amounts to different groups

  3. Type of Variable: Vary the type (e.g. Duduk di hadapan vs belakang)
• Individual Differences Manipulation


  Varying the IV by selecting participants based on their internal state (e.g. M/F, Level of Self-Esteem)
• Fixed variables


  Variables that are not experimentally manipulated (e.g. sex, age, personal characteristics)
• Fixed variables selected as IV are not experimentally manipulated, so both groups receive similar treatment, making it a within-subjects design rather than a between-subjects design
• Baseline is required in between-subjects design for matching of subject purpose, not for M/F comparison
• If baseline is taken and scores are not equal between groups, the design will turn into a within-group factorial design
• Responses Used in DV

  • Questionnaire
  • Verbal reports
  • Physiological responses
  • Behavioral performance
• Setting


  Characteristics that vary from one environment or circumstances to another
• Organism


  Characteristics that vary from one living thing to another