Distribution

• Normal Distribution Curve

  Label

  A) 34

  B) 34

  C) 13.6

  D) 13.6

  E) 2

  F) 2

  
• Skewed Distribution

  Positive skew:

  • Mostly low scores
  • Mean is affected by some extremely high scores
  • Mean is skewed in a positive direction (right)

  Negative skew:

  • Mostly high scores
  • Mean is affected by some extremely low scores
  • Mean is skewed in a negative direction (left)
• Skewed Distribution Curve

  Label

  A) Positive

  B) Negative

  
• Normal Distribution

  • Represented by bell-shaped curve
  • Symmetrical at mid-point
  • Tail ends not touching horizontal axis
  • Further from centre, more abnormal; most scores are close to mean
  • Some claim behaviour is abnormal if it is two SDs (or more) above/below mean
  • Abnormal distributions are skewed
  • When large sample used
  • Possible to examine overall data distribution
  • By converting each score frequency into percentage
  • (score frequency/total score number) * 100