Distribution and correlations

• What is normal distribution and where can you find it?

  • Can be shown on a histogram
  • Mean, median and mode are very similar to each other
  • Perfectly symmetrical
  • Bell-shaped curve
• What is a skewed distribution and where can you find it?

  • Mean is not very representative (most scores are higher or lower than the mean - therefore it shouldn't be used as sole measure of tendency)
  • Positive = right =big mean
  • Negative = left = small mean
• Distribution graphs

  
• What is a correlation?

  A measure of how strongly two or more variables are related to each other.

  • Variables are known as co-variables
• What is a correlation co-efficient?

  A number given to the correlation to describe its strength.
• Correlation graph

  
• What is a strength of a correlation?

  Precise and quantifiable measure.
• What is a strength of a correlation?

  Quick and economical
• What is a strength of a correlation?

  No manipulation of the IV or DV needed
• What is a limitation of a correlation?

  Tells us how they're related, but not why.
• What is a limitation of a correlation?

  May have an unknown intervening variable.
• What is a limitation of a correlation?

  No IV or DV, so can't establish cause and effect.