Measures of central tendency and dispersion

• Mean: Add up all the scores, divide by number of scores.

  
  

  +)Includes all the values in the data set.

  
  

  -)May be unrepresentative because one very large or small number can distort it.
• Median: Middle value

  
  

  +)Less affected by extreme scores because it only focused on middle number.

  
  

  -)The higher/lower values are ignored, may be important.
• Mode: Most frequent value.

  
  

  +)Relevant to discrete data (data in categories)

  
  

  -)Overly simple and may not be useful when there are multiple modes.
• Range: Difference between highest and lowest value.

  
  

  +)Easy to calculate, easier than standard deviation.

  
  

  -)Doesn't account for the distribution of scores.
• Standard deviation: Measure of the average spread around the mean. (e.g. lower standard deviation means that there is more similarity between values, higher stand deviations means more deviations between values).

  
  

  +)More precise than the range, includes all values within the calculation.

  
  

  -)Can be misleading as it can be distorted by extreme values.