It would be very bad if they only used actual loss only. What happens if you hit a jackpot and win $10,000? No comps next month? They must use some combination of actual loss and amount played. That is why when I am at a table I squirrel away chips frequently. Most times I end up break even or ahead when they think I have lost. Of course, I am a small bettor so it does not matter that much - I am happy to get a free room and a meal or two. But these days even that is getting hard to get.