# When doubling on J or B, anyone else notice. . .

#### LRDell

##### Experienced Member
PABaccred
Anyone noticed that the house has a distinct edge when doubling up on Jacks or Better Video Poker? I noticed this at both microgaming casinos where I was playing and decided to check it out statistically. According to the customer service people at both casinos the cards dealt when doubling are randomly generated. HAH! I sent this information to both casinos. Know what I got back - NOTHING.

I documented and analyzed 308 hands of Jacks or Better poker on which I attempted to double my winnings. Realizing that what card you start with is not the critical factor, but the cards that are dealt to the house and what chances your card has to beat it. Since the house is dealt four cards, you have a 0% chance (all house cards are higher), 25%, 50%, 75%, or 100% (all house cards are lower). Here were the results:

On 242 hands on which I attempted to double \$5 in winnings to \$10, the house had a distinct and clear edge of 4%, based on the means, with 41 percent of hands having a less than 50% chance of winning and only 37 percent of hands have greater than 50% chance of winning.

It becomes even worse when attempting to double \$10 in winnings to \$20. Although there were only 62 hands, this is quite enough to come up with an everage and a mean that should only vary slightly from a larger number of hands. The house edge in this situation was 7%, with only 33% of the hands having a greater than 50% chance of winning, compared to 40% in the less than 50% category. Lots more high cards for the house and 0% chances, too.

Don't even ask about the few times I tried to make \$20 into \$40. On four attempts the house averaged a Jack as deaer card and a winning percentage 87%, three out of four of the hands giving the bettor 0% chance of a win. Four hands is not statistically significant, but given the other numbers, it certainly wasn't surprising.

Is it better to just not attempt to double?

I only double on playtech's JoB because they count doubling as wager. Doubling actually lower the variance and house edge. I also earn extra comps for doubling. After thousands of doubling, I believe playtech's doubling game is fair.
I am not sure whether MG or RTG's doubling games are fair or not. One player in WOL used to get decent win with 10 straight winning (1 in 2280 chance) on RTG's VP so I guess RTG is fair as well.
I doubled twice on MG's JoB by mistake and I lost them both. Chance of this to happen is 21.3% so I am not complaining.

I double quite often in both MG & Playtech (as well as RTG when I play there) and I get pretty varied results on the first double making me think its fair. The 2nd one only sometimes is as varied though, at least at MG. MANY times the dealer will pull an ace on the 2nd double. Funny how that happens. I've rarely gotten past 3 doubles when I"m feeling real lucky.

For the whole story of 10x straight won on doubling, read here:

Truely amazing. :notworthy

LRDell:
I have not calculated the probabilities, because including the possibility of equal cards is messy, but my gut feeling is that you were not even exceptionally unlucky.

GrandMaster said:
LRDell:
I have not calculated the probabilities, because including the possibility of equal cards is messy, but my gut feeling is that you were not even exceptionally unlucky.

I did actually do some research on the probabilities, and the only slight variation from 50% above and below the mean would be from the dealer's card being removed from the stack of possible player cards, which only minutely changes the odds. If the dealer card is dealt randomly, it should be below 8 an equal number of times it is above 8 and the same goes for each of the potential player cards.

Where the lack of randomness showed the most is the number of times the house dealt up a player's cards that had only 25% or 50% against dealer cards like 5,6,7. I split the equal card probabilities between the player and the house.

My only point was to show that I don't believe they are randomly generated, particulalry since the house odds got substantially better the more money was on the line, and to ask if anyone had tried it without ever doubling and what their results were. Didn't mean to whine.

I have noticed on microgaming that it seems to pull out aces and kings a lot for their upcards. Especially on the 2nd double.

And it seems to happen more on a big hand. Say 25 bucks or more and I usually dont double cause I know if I tried an ace is the 1st card out and the only thing you can hope for is a tie.

I also noticed that on playtech if you get past the 1st you can usually get on a roll. I have double up to 4 or 5 times in a row a lot, but chicken out past that cause I didnt want to lose what i had. I hate their blackjack and think it is rigged but poker seems pretty fair. At least doubling.

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Well after seeing the 10x doubler on RTG vp, I decided to give it a try myself. Cashed in about 4 bux worth of comp points and here's the result... (started with 2 pair, or 10 nickels payout)