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Thread: EV and Variance calculation

  1. #1


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    EV and Variance calculation

    Hello everyone! Greetings from Argentina!!!
    I am new here and this is my first post. I have a question that is creating me a lot of confusion:

    If i play 1 spot or 2 spots with 75% bet each, my RoR should remain constant. I use powersim to get this info and so far so good.

    Yet when i go to qfit calculators and it asks me for EV SD and hands played , i dont know what to introduce here. For 1 spot is pretty much straight fwd but what happen when i am trying to find the answer for 2 spots?
    As i am betting 1.5x wager per round should i introduce a 1.5x EV and same variance? Should i keep same EV and variance but increase number of hands times 2?

    I want this info to calculate things such as probability of reaching a target or actual results among other things...

    I hope my question is clear and hopefully somebody can explain it for me.

    Thanks!

  2. #2
    Random number herder Norm's Avatar
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    You should run a sim with the desired parameters and use the results.
    "I don't think outside the box; I think of what I can do with the box." - Henri Matisse

  3. #3


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    I wish i could but powersim doesnt allow you to indicate you will play 2 spots or 1. So for variance calculation i just enter the ramp in 1 spot and with that i get the variance per round which by definition should be the same as when i bet 75% each in 2 spots.
    Now when it comes to ev and number of hands i honestly dont know what to consider.
    Should i assume my ev is the ev of the 2 spots summed, with variance and number of hands remaining constant? Should i keep both ev and variance as if i were playing 1 spot but increase the number of hands? Or should i assume that nothing changes about playing 1 or 2 hands simultaneously?

  4. #4


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    Quote Originally Posted by condor19286 View Post
    I wish i could but powersim doesnt allow you to indicate you will play 2 spots or 1. So for variance calculation i just enter the ramp in 1 spot and with that i get the variance per round which by definition should be the same as when i bet 75% each in 2 spots.
    Now when it comes to ev and number of hands i honestly dont know what to consider.
    Should i assume my ev is the ev of the 2 spots summed, with variance and number of hands remaining constant? Should i keep both ev and variance as if i were playing 1 spot but increase the number of hands? Or should i assume that nothing changes about playing 1 or 2 hands simultaneously?
    There are several considerations. First, if you don't sim, you won't get perfectly accurate results, but as a generality, e.v. is increased by 50%, as you are betting 50% more per round. However, this is offset by the eternal observation that you are using 50% more cards per round, if you are playing alone, and so you are gaining virtually nothing at all in hourly e.v. With more players at the table, there is a gain, and that has to be determined after you stipulate how many are at the table.

    Second, and this is where you are making a fundamental mistake, ROR and variance are NOT the same thing! The total variance for playing two hands of 75% is NOT the same as the one-hand, 100%, variance. The two-hand variance is more, and it is more by the same 50% increase, which is why the ROR (but not the variance!) remains the same. ROR is proportional to the e.v./var, and so if each increases by 50%, the overall ROR doesn't change. Is that clear?

    Don

  5. #5


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    Don,
    First of all, thank you so much for answering.

    So if i get you correctly, ev for 2 spots should be ev*1.5 and for std dev is std * SQRT(1.5)

    When considering number of hands i should consider number of ROUNDS in BJA calculations for probabilty of reaching a goal, etc...

    Is that it? Did i get it right?

  6. #6


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    Quote Originally Posted by condor19286 View Post
    Don,
    First of all, thank you so much for answering.

    So if i get you correctly, ev for 2 spots should be ev*1.5 and for std dev is std * SQRT(1.5)

    When considering number of hands i should consider number of ROUNDS in BJA calculations for probabilty of reaching a goal, etc...

    Is that it? Did i get it right?
    Yes! :-)

    Don

  7. #7


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    Quote Originally Posted by DSchles View Post
    Yes! :-)
    Don
    Thanks again Don!
    I have one more doubt here: if i run a sim in PowerSim with the bet ramps of each spot, can i sum the variances of each of the two and get same result as with the proposed calculations you confirmed before? Same principle would apply for ev?

    Example:
    if ev in one spot is 500, for 2 spots it should be 750. If i run sims for each of these spots, i should get 375 each? (asumming wagers per each are properly calculated to keep RoR the same)

    (imagine the same for Variance)

  8. #8


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    Quote Originally Posted by condor19286 View Post
    I have one more doubt here: if i run a sim in PowerSim with the bet ramps of each spot, can i sum the variances of each of the two and get same result as with the proposed calculations you confirmed before? Same principle would apply for ev?
    I'm sorry, but I have no idea what PowerSim is. But, no, you can't sum the variances of the two spots because of the covariance between the two spots, which needs to be reckoned. In general, see the formula in my book, in the p. 20 footnote, which is adapted from Griffin.

    Quote Originally Posted by condor19286 View Post
    Example:
    if ev in one spot is 500, for 2 spots it should be 750.
    Yes.

    Quote Originally Posted by condor19286 View Post
    If i run sims for each of these spots, i should get 375 each? (asuming wagers per each are properly calculated to keep RoR the same)
    Sure. But nothing is going to be identical. They are, after all, two different hands.

    Quote Originally Posted by condor19286 View Post
    (imagine the same for Variance)
    Not sure what you're asking here. If you play two simultaneous hands, naturally, with a large enough sample, all the stats pertaining to one of the hands should be more or less the same as the stats for the second hand. Why would it be otherwise?

    Don

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