i think that 6 months data is irrelevant. any thing can happen within that 6 month period. i prefer to use a minimum of 5 years to determine if something is going to work. this way you have looked at many thousands of selections and many, many thousands of horses. what i do agree with is your pattern of checking. i use 1997 to 2002 as my basis data for checking my concepts. if it has worked at say a 15% profit, then i check how that idea worked over the full year of 2003. if it still stacks up over that 12 month period...then i think i may be on to something.

markallan