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#1
11-25-2005, 04:34 AM
 dink Senior Member Join Date: May 2003 Location: Townsville, Australia Posts: 183
10% refund question

Does getting a 10% refund on Black Jack losses at totalbet, make BJ a +EV game?

simple question...

#2
11-25-2005, 08:30 AM
 Guest Posts: n/a
Re: 10% refund question

HELL NO

It gives you 10% of your losses, meaning 1/10th of what you lose, not what you wager. So instead of losing \$500 you lose \$450. [img]/images/graemlins/wink.gif[/img]
#3
11-25-2005, 10:17 AM
 scrapperdog Junior Member Join Date: Dec 2004 Posts: 26
Re: 10% refund question

Depends on how often they give it. If you get 10% of your losses back at the end of each hand that would give you a huge edge. If they give it at the end of the month it is pretty much worthless.
#4
11-25-2005, 11:26 PM
 Guest Posts: n/a
Re: 10% refund question

It all depends on the granularity. As Scrapperdog said, if it's per hand, it's a huge advantage -- you lose just over half your hands in BJ, so a 10% refund is worth over 5% overall. A 5% edge at BJ is unheard of.

But they probably award it per month, or something like that. If you play 100,000 hands per month at \$10 each, and the house advantage at BJ is 1.0%, then you will have lost, on average, 1.0% x 100,000 x \$10, or \$10,000. Getting back 10% of that is a refund of \$1000, reducing the house edge from 1.0% to .9%. That's not worth a whole lot.

Somewhere between the two extremes is reality. If you chose to play just a few hands per month, ten or twenty, you're effectively playing just one tiny session. Odds are pretty high that the session will have some wild variance. If you win big, great. If you lose big, you get a big 10% refund. The advantage of 10% back on the loser can actually make it a net positive game.

To have the 10% effect big enough to make it a winning game, you have to play so few hands (per refund) that you're not experiencing a long term average at all. You have to be experiencing mostly variance. . . This can be fun if you enjoy individual gambles and you want to place some bigger wagers. If you can't afford that, or don't get a thrill from playing 10 or 25 hands per month, you can't pull off the +EV trick. If you play enough hands per refund, you are guaranteed a refund every month simply because you are guaranteed a loss!

It would be interesting for someone to calculate how many hands per month can be played with a 10% loss refund to equate to a real house advantage of 0%.
#5
11-27-2005, 10:58 PM
 AcmeSalesRep Junior Member Join Date: Aug 2004 Posts: 25
Re: 10% refund question

[ QUOTE ]
It would be interesting for someone to calculate how many hands per month can be played with a 10% loss refund to equate to a real house advantage of 0%.

[/ QUOTE ]

It is right around 3 hands...

Acme
#6
11-27-2005, 11:15 PM
 mr_whomp Junior Member Join Date: Apr 2005 Posts: 5
Re: 10% refund question

yes it makes it +EV (bet all the money on one hand. If you win cash out the winnings and do it again. Keep on doing it until you bust. Overall it would end up being (on a 10\$ bet):

something like 50.5% chance of losing 9 bucks
49.5% chance of winning 10 bucks - doesn't take into account blackjacks/doubling.

Now the question is, are you better off betting half of your money so that you can double/split if you win?
#7
11-27-2005, 11:20 PM
 Jimbo Senior Member Join Date: Sep 2002 Location: Planet Earth but relocating Posts: 2,193
Re: 10% refund question

[ QUOTE ]
[ QUOTE ]
It would be interesting for someone to calculate how many hands per month can be played with a 10% loss refund to equate to a real house advantage of 0%.

[/ QUOTE ]

It is right around 3 hands...

Acme

[/ QUOTE ]

The correct answer is zero but at least you are getting closer to understanding it is -EV.

Jimbo
#8
11-27-2005, 11:31 PM
 AcmeSalesRep Junior Member Join Date: Aug 2004 Posts: 25
Re: 10% refund question

[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
It would be interesting for someone to calculate how many hands per month can be played with a 10% loss refund to equate to a real house advantage of 0%.

[/ QUOTE ]

It is right around 3 hands...

Acme

[/ QUOTE ]

The correct answer is zero but at least you are getting closer to understanding it is -EV.

Jimbo

[/ QUOTE ]

Yawn...Dumbo continues to spew his worthless drivel...At least here he makes it public instead of the garbage he keeps sending to my private box...

Oh...and since the [censored] for brains will not quit spamming me...

&lt;&lt;You are now ignoring this user. You will no longer see the body of any of their posts.&gt;&gt;

Acme
#9
11-28-2005, 01:21 AM
 Guest Posts: n/a
Re: 10% refund question

[ QUOTE ]

Now the question is, are you better off betting half of your money so that you can double/split if you win?

[/ QUOTE ]

If you want to assume something like a house edge of 1%, you must assume that money is available for doubling/splitting. Otherwise, the house edge is far greater than 1%.

Since people are being silly with numbers, I actually wasted some time on an estimate.

Assume that BJ is a 1:1 game where you win .495 of the time and lose .505 of the time. This makes it a 1% house advantage game, and ignores doubles, splits, and blackjacks.

If you play one hand per month, taking your refund if your one hand loses, your edge is 4.05%. If you're betting \$10, you expect to earn \$.405. Almost fifty cents! By the way, you'll never earn as much as fifty cents.

If you play two or three hands per month, your edge is 1.550%. Yes, it's the same for even and odd numbers of hands played. For two hands, you expect to make .31005 on \$20 wagered, and for three hands, you expect to make .46508 on \$30 wagered. .31005/20 and .46508/30 are the same. Fourty-six cents is about the most you can make -- it will go down as more hands are played.

If you play four or five hands, your edge is .925%.

Six or seven, .613%.

Eight or nine, .418%.

Ten or eleven, .281%.

Twelve or thirteen, .179%.

Fourteen or fifteen, .098%.

Sixteen, -.171%.

So if flips negative at sixteen bets. Fifteen bets is a slight winner.

Again, this is an approximation of blackjack, which does not always pay 1:1. The whole .495/.505 thing is an approximation.

I didn't develop a general answer; I just made a spreadsheet layout that let me insert more rows to get the answer. Here's the data for 14 bets:

<font class="small">Code:</font><hr /><pre>\$ Real \$ Base W L Exp Freq Net Exp EV
140 140 14 0 5.3024E-05 1 5.3024E-05 0.007423365
120 120 13 1 5.40952E-05 14 0.000757333 0.090879985
100 100 12 2 5.51881E-05 91 0.005022114 0.502211364
80 80 11 3 5.6303E-05 364 0.020494282 1.639542554
60 60 10 4 5.74404E-05 1001 0.057497847 3.449870791
40 40 9 5 5.86008E-05 2002 0.117318838 4.692753534
20 20 8 6 5.97847E-05 3003 0.179533374 3.590667477
0 0 7 7 6.09924E-05 3432 0.209326069 0
-18 -20 6 8 6.22246E-05 3003 0.186860519 -3.363489342
-36 -40 5 9 6.34817E-05 2002 0.127090319 -4.575251495
-54 -60 4 10 6.47641E-05 1001 0.0648289 -3.500760614
-72 -80 3 11 6.60725E-05 364 0.024050391 -1.731628146
-90 -100 2 12 6.74073E-05 91 0.006134064 -0.552065791
-108 -120 1 13 6.87691E-05 14 0.000962767 -0.103978825
-126 -140 0 14 7.01583E-05 1 7.01583E-05 -0.008839951
16384 1.00000 0.137
0.098%
</pre><hr />
Explanation:

Each row is one combination of wins/losses; for example, third column is for all outcomes with 12 wins and 2 losses. Assuming a \$10 bet, this results in the Base winnings listed. The Real winnings is the same as the Base, but 10% is refunded if the amount is negative.

The Exp shows how often you expect the given combination of wins and losses to hit. For the third row, the number is (.495^12 * .505 ^ 2). (The 12 and 2 are taken from Win and Loss columns.)

Freq shows how many ways there are to get that combination of wins and losses. There's only one way to get 14 wins and no losses (as in row one); if there is one loss, the loss can be the first hand, the second, etc., for 14 ways to have one loss (as in row two). Etc. The number in the column are basically the fourteenth row of Pascal's Triangle. The checksum at the bottom is just the total, which must equal 2^14, which it does.

Net Exp is just Exp * Freq; it shows what fraction of the time that combination hits. The checksum at the bottom is the total, which must equal 1.0, which it does.

EV is the Net Exp frequency times the \$Real value; it's the EV in dollars for a \$10 bet for that combination. The sum at the bottom -- \$.137 -- shows the expected winnings.

Divide the winnings of \$.137 by the amount bet of \$140 and you get the .098% return.

Mind you, to achieve that return in real blackjack, you would have had to be willing to double and split as appropriate, so the \$140 wagered could be more like \$180 or \$200, reducing the % return, but that's moot -- it's still positive, and it will still flip negative at sixteen bets.

It's really a genius bonus for the casino to offer the players. . . From the casino's perspective, they only give up .01%. A player with a winning month gets nothing, but a player with a losing month gets a nice 10% return, and if feels like 10% to them. For players who haven't tried gambling yet, the idea of 10% back on a loss feels like 10%. Only smart players (who wouldn't play online BJ anyway, except for bonuses) aren't enticed by the phony number. The players who get the biggest "return" are the regular gamblers who are likely to come back and lose month after month, and that's the people the casino really wants to give the most incentive to return.

Genius, I say, genius. If only I could find a similarly effecive way to get donks to migrate to my poker tables. . .

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