Distributions

• Normal


  plots the spread of scores on certain variables

  normal distribution is symmetrical so forms a bells-shaped curve

  mean, median and mode all occupy the exact middle of the curve, with fewer people at extreme ends
• Skewed


  some distributions won't be symmetrical and produce a distribution that leans to left or right

  means that the distribution of data around the mean is skewed
• Positive skew


  mean = biggest

  median = middle

  mode = smallest

  a difficult test would produce this skew

  
• Negative skew


  mean = smallest

  median = middle

  mode = biggest

  an easy test would produce this skew