Measure of central tendency

• mean 


  add up all the values and divide them by the number of values in the list.

  +most sensitive measurement as all the values are included

  -is affected by extreme scores so may be inaccurate.
• Median 


  Middle value in numerical order. If there is an even number of values, can find the average of 2 middle numbers.

  +unaffected by extreme values as only focuses on the middle value.

  -less sensitive as doesn't use all the values.
• Mode


  most frequent occurring value in the list of numbers.

  +used in discrete categories and unaffected by extreme values.

  -not sensitive as not all values are used.
• Range 


  finding the differences between the highest and lowest score in a set of data.

  +easier to calculate

  -may give inaccurate portrayal of spread of data if any anomalous results.
• Standard deviation 


  numerical value that expresses spread id data around the mean. The higher the SD the greater the spread of data from the mean. The lower SD the closer the data is which means PP scored similar scores.

  +more sensitive as all values are used and less likely to be influenced by anomalous data.

  -time consuming and harder to calculate.