How to understand the netprofit(IS/OOS ratio)?

Hello,

I’m a little confused about this setup.

 

According to the literal meaning, I guess the net profit(IS/OOS ratio) is net profit in IS / net profit in OOS.

IF the net profit in IS is 1000$, net profit in OOS is 400$, so the net profit(is/oos ratio) is 250%.

But in the ebook, it’s been described below,

”

If strategy makes $6000 on whole In Sample period, and $4000 on Out of sample period, then its Net
Profit (IS/OOS Ratio) will be 66.6% (because $4000 is 66.6% from $6000).

”

So the IS/OOS ratio means that performance in OSS / performance in IS?

If I want that the performance in OSS is 60% better than in IS at least, I should set “dismiss when IS/OSS ratio is below 60%”?

 

This ratio only makes sense if the IS and OOS has the same length. Otherwise i would have to be adapted to the difference in length as well which it probably is in the eBook.