thomas :
of course , attempts are made to make data comparable .
i question how useful the resulting information is after it has been massaged .
if 'adjusted' data is used to arrive at statistcs/information , at least it should be stated what adjustments were made and what the information looks like before and after adjustment .
my experience has been that is not always possible to smooth/adjust/massage data and still come up with reliable information .
i'm not saying that no attempt should be made to gather and compare stastical information. but as stated above , one needs to know how the input was manipulated , and caution should be used when using such output(information/stats).
(i think i posted this story before ; so pls skip it if you wish . it comes out of my almost thirty years experience in the life insurance industry . of course , the insurance industry would not exist without statistics . number crunching is a must before the actuary grabs pencil and paper to make the 'real' decision .
here goes : a group of actuaries were lost in the woods . they came to a river and had to decide if it would be safe to cross on foot . the junior actuaries were given the task to make the necessary calculations , so a decision could be made on whether it would be safe to wade across .
the juniors calculated the average depth to be 4foot 6 , and it was decided to cross the river .
of course , none of the actuaries made it across - they all drowned
- unfortunately no one could swim either .
actuaries always had a lot of those 'jokes' to tell , to illustratte how dangerous it is to use statistics without understanding the underlying data - a favourite term our chief actuary used was "to put on a thinking cap" after all the data had been crunched and before making a decision - he didn't want to drown ! ).
'nuff for now .
hbg