The scores on a (hypothetical) vocabulary test of a group of 20 year olds and a group of 60 year olds are shown below.
20 year olds: 27 26 21 24 15 18 17 12 13
60 year olds: 26 29 29 29 27 16 20 27
- Test the mean difference for significance using the .05 level.
- List the assumptions made in computing your answer.