Ordinal = numbers that only tell you the order e.g. highest score, second highest score, third highest score etc. You have no idea how big the gaps are between 1st, 2nd, 3rd etc and the gaps will be uneven. Something like old middle aged and young might be used in psychology. IQ scores are ordinal.
Interval = a bit like ordinal but the intervals between scores will be even - e.g shoe size - a size 40 is the same distance from a size 41 and it is from a size 39. I can't think of a psychological example off the top of my head :(
Ratio = a bit like interval because the gaps between scores are identical but this time a score of, say, 8 will be twice the size as a score of 4. This is obviously not true of shoe size where size 50 feet aren't twice the size of size 25. Age is ratio as it makes sense to say that a 50 year old is twice as old as a 25 year old.
Answered Thu 28th March, 2013 @ 11:49 by janet m Edited by janet m on Thu 28th March, 2013 @ 13:25