descriptive statistics

• what are 'Descriptive statics '?

  Express numbers in a way that gives an immediate impression of the overall pattern of results  
• what does it mean by 'Measures of dispersion'?

  How spread out the data is  

  • e.g., range, standard deviation  
• what does it mean by 'Measure of central tendency  '?

  Typical value of data  

  • e.g., mean, medium, mode 
• what are Graphs and tables used for?

  Visual summary  
• what is Standard deviation ?

  How far each score is from the mean, on average  
• Low standard deviation?

  Data is not very spread out and scores are close to the mean 
• High standard deviation?

  Data is very spread out and scores are far from the mean 
• what are the strengths of standard deviation?

  • More precise than range  
  • Includes all scores  
• what are the weaknesses of standard deviation?

  It can greatly by extreme score  
• a strength of the mean?

  Includes all scores so represents all data  
• what is the limitation of the mean?

  Easily distorted by extreme scores which makes it unrepresentative of entire data  
• a strength of the mode?

  Easy and simple to calculate  
• a limitation of the mode?

  Can be quite unrepresentative of the data  
• a strength of the range?

  Easy and simple to calculate  
• a limitation of the range?

  Can be affected greatly by extreme scores  
• a strength of median?

  Isn't affected as much by extreme scores  
• a limitation of the median?

  Doesn’t include all scores in the final calculation so it isn’t representative of the whole data