Descriptive Statistics

Descriptive Statistics

1. Mean

   • 'The Average' - A way of indicating where most of the scores lie when there is a collection of scores.
     • Add up all the scores and divide the sum by the number of scores.
       • The trouble with the mean is that an extreme score might make the average score artificially high or low.

2. Median

   • The value that divides the distribution of scores in half.
     • Put the scores in ascending order. if there is an odd number of scores the median is the middle score.
   • If there is an even number of scores, put them in ascending order and average the two middle scores.
     • In either case, half of the scores in the set will be above the median and half will be below it.

3. Mode

   • Most frequently occurring value in a set of scores.
     • Bi-modal score - sometimes there can be two modes.

4. Range

   • Simplest measure of 'spread-out-ness' or dispersion is called the range.
     • Range is the difference between the highest and the lowest score.
       • Cannot give an accurate description of a group of scores where an odd score is much higher or lower than the rest.
   • Subtract the lowest score from the highest score.
     • Gives a good indication of the spread of scores, it depends completely on just two scores - highest and lowest.