data analysis: descriptive statistics

• mean


  add them all up and divide by the number there all is
• median 


  middle value
• mode


  most frequently occurring
• range


  subtract the lowest from the highest and add 1
• standard deviation


  measures how much scores deviate from the mean
• mean (evaluation)


  + most sensitive and representative

  +easily distorted
• median (evaluation)


  +not affected by extreme values

  -less sensitive than the mean
• mode (evaluation)


  +easy to calculate

  -crude, unrepresentative
• range (evaluation)


  +easy to calculate

  -may be unrepresentative of the data set
• standard deviation


  +much more precise than the range

  -can be distorted by extreme values