Pr2

• Factors Affecting Experimental Plan

  • History
  • Maturation
  • Testing
  • Mortality
  • Interaction Effect
  • Measuring Instrument
  • Statistical Regression
  • Differential Selection
  • John Henry Effect
• History


  Unexpected events that occur during first and second measurement during experimental period that affect the results of the experiment
• Maturation


  The process of maturing of the participants either biological or psychological during the course of experiment regardless of the event may affect the result of the study
• Testing


  The subject may be aware of the contents of post-test because of the same contents in pre-test. So the subject learns from pre-test rather than the treatment
• Mortality


  The loss of the subject from comparison group could greatly affect the results of the study. The subject may drop out of the experimental plan or suddenly disappeared during the course of the study
• Interaction Effect


  The result of the study was affected by the extraneous factors such setting, time and condition of the experimental set-up
• Measuring Instrument


  Changes in calibration of instrument, observers, and scorers may cause changes in the measurements of the variables
• Statistical Regression


  When the pre-test of the subjects is extremely far from their score in post-test. This threat is caused by the selection of subjects on the basis of extreme scores or characteristics
• Differential Selection


  Selection of individuals with different previous knowledge or ability which would affect the final measurement of the study
• John Henry Effect


  Henry outperformed a machine under an experimental setting because he was fully aware that his performance was compared with that of a machine. The subject in the controlled group is aware of their disadvantage, thus working harder to outperform the experimental group