data analysis: descriptive statistics

data analysis: descriptive statistics

1. measures of central tendency

   • averages which tell us the most typical values in a set of data
     • mean
       • adding up and dividing by how many there are
       • most sensitive - includes all data
         • more representative
       • can be distorted by extreme values
         • not representative
     • median
       • middle value - in ascending order
       • extreme scores don't affect it
       • less sensitive - not all values taken into account
       • easy to calculate
     • mode
       • most frequent value
       • may have more than one = bimodal
       • easy to calculate
       • not really representative

2. measures of dispersion

   • spread of scores
   • range
     • calculates the spread of scores
     • take away the lowest value from the highest value
     • sometimes add 1 to round it
     • strengths
       • easy to calculate
     • limitations
       • only takes the most extreme values no others
         • might not be representative
   • standard deviation
     • high far scores deviated from the mean
     • the larger the SD the greater the spread
       • the IV didn't affect everyone the same
         • maybe anomalous results
     • low SD = participants acted the same
     • more precise
       • includes all values
         • however can be distorted more easily