Putting the cart before the horse?

[Herman van den Bergen <psytek@xxxxxxxx>]

My system development sequence has always been (and I believe many others
work this way too):

1) Performe my first System Tests on historical data preceeding 2001. 
2) If the results look promising, I would perform a system test on more
recent, 2001 data.
3) If that looks good too I may assume my system to be valid and continue
work on it, if not I modify the system and start all over again.

So, each testing phase includes extensive historical testing. Isn't this
like putting the cart before the horse? After all, if my system doesn't
make money during the most recent six months, why would I be interested to
learn whether it earned money a long time ago? The fact is that if it
didn't show profits in recent months I am not going to use it no matter how
good it appeared to be in the past. Would you?

So, unless somebody can straighten me out, I'll be, from now on, testing my
systems on recent data first and then, only if it shows profit in recent
months, will I verify it's performance on historical data to get to know
the system better.

Looks like this will save me a lot of time... right or wrong?

Happy development!
Herman.