ABSTRACT
In the previous chapter we saw that the variability of the scores between the conditions arose from systematic differences between conditions plus random errors. In the independent measures design there are different subjects providing the scores for the different conditions, so part of the between conditions variance will be due to individual differences between the subjects. This is a random error as we are not systematically varying subjects across the conditions. The other random errors can be termed experimental error as we will always get some random errors in any experiment despite our attempts to provide equivalent conditions for the subjects. The between conditions variance can be seen as arising from three sources: systematic differences between the conditions, individual differences and experimental error.
