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MDF calculation - betters bet or callers call?? ... and meaning

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  • MDF calculation - betters bet or callers call?? ... and meaning

    Quiz on Pre-Flop was as follows - and gave the answer below that - but isn't the BB bet only 2.5 in that he's already put IN 1 BB ?????


    If you raise to 3.5bbs from the small blind, what is the minimum defense frequency from the big blind player?


    Answer from site: To solve for MDF, MDF = 1 - bet/(bet + pot) = 1 - 3/(3+1.5) = 33%


    But shouldn't it be 1 - 2.5/(2.5+1.5) ??

    Is the "bet" in the MDF calculation from the perspective of the bettOR - or the caller???


    Also - why IS this called MDF - if it doesn't actually signify that we should be defending at least that frequency???

  • #2
    MDF is determined by the player making the bet. To better understand MDF look at its purpose.

    The purpose of MDF is to prevent the betting player to auto-profit from their bluffs. If there is a $100 pot, and a player bets $100 into that pot, if his opponent folds more than 50% of the time he auto-profits from his bluffs and therefore he is incentivized to bluff frequently.

    Comment


    • #3
      Great to know that's from the better's perspective. Okay, and then by knowing that MDF is 33% there (assuming that's right), then how is the better making use of that information? Deciding bet size based on estimation of villain's range??? Apologies - I can be slow on the uptake but I think once I absorb it, I've got it...!! Thanks!

      Comment


      • jjpregler
        jjpregler commented
        Editing a comment
        The actual formula is you should bluff at the same frequency as the pot odds you give them. So if you do bet pot and you are giving your opponent 2:1 pot odds, your value:bluff should be 2:1.

        However, on the flop and turn we don't typically use this ratio, since our bluffs would have equity in the hand. When we bet flop we would be 2 bluffs:1 value, on the turn it is typically 1:1.

        This way a balanced bluff range will give the caller 0EV on his calls with bluff catchers. The whole process is reducing to the Principle of Indifference in Game Theory. You want to bet in such a way that your opponent is indifferent with his bluff catchers.

        In general Jonathan teaches the 2:1 bluff:value on the flop, 1:1 on the turn and 2:1 value:bluffs on the river. Note these won't always be perfect based on different sizings, but it is close enough and it is an implementable strategy that can be developed and used in the game. The human mind cannot solve in the way a computer can, so we need certain shortcuts to help us get to a close, but implementable strategy.

        In the Tournament Masterclass, all of this is discussed more deeply.
        Last edited by jjpregler; 04-18-2021, 02:03 PM.

    • #4
      Originally posted by acercap View Post
      Great to know that's from the better's perspective. Okay, and then by knowing that MDF is 33% there (assuming that's right), then how is the better making use of that information? Deciding bet size based on estimation of villain's range??? Apologies - I can be slow on the uptake but I think once I absorb it, I've got it...!! Thanks!
      Well...the bettor can use the information to ask the question "how often does this bluff need to work to be profitable?" Then he can decide whether he thinks it will work that often.

      But in GTO land it's more typical for the caller to calculate it (still from the bettor's perspective), and then purposely ensure he calls enough that the bet is not profitable.

      Comment


      • #5
        I also have a question regarding this quiz. Pokercoaching says to solve for MDF, MDF = 1 - bet/(bet + pot) = 1 - 3/(3+1.5) = 33%.
        But other sources i.e upswing poker says bet/(bet + pot) for MDF and it gives the opposite side of percentage 66%.
        Im confused.

        Comment


        • #6
          Originally posted by IceFishingEnthusiast View Post
          I also have a question regarding this quiz. Pokercoaching says to solve for MDF, MDF = 1 - bet/(bet + pot) = 1 - 3/(3+1.5) = 33%.
          But other sources i.e upswing poker says bet/(bet + pot) for MDF and it gives the opposite side of percentage 66%.
          Im confused.
          Bet / ( Bet + Pot )

          This is what we use as the bettor to determine how often our opponent needs to fold for us to automatically profit.

          Here's an example. The pot is 15bb and I bet 5bb. At what frequency does my opponent need to fold for me to automatically profit? 5 / ( 5 + 15 ) = 25%.

          So if my opponent folds more than 25% of the time I can bet with any two cards because I know I'm automatically going to profit.

          1 - Bet / ( Bet + Pot )

          This is the MDF calculation. It is simply the inverse of the previous calculation.

          Using the same example as before but from the other point of view. The pot is 15bb and my opponent bets 5bb. At what frequency do I need to defend to prevent my opponent from automatically profitting? 1 - 5 / ( 5 + 15 ) = 75%.

          So I need to defend with at least 75% (minimum defence frequency remember!) in order to prevent my opponent from automatically profitting.


          Can you see how the two numbers work together? Forcing a fold more than 25% of the time is the same as the other player having to defend at least 75% of the time.

          Try the calculations yourself with different pot sizes and bet sizes and it should become a lot clearer.

          Give me a shout if you still need this clearing up.

          Comment


          • jjpregler
            jjpregler commented
            Editing a comment
            Upswing Poker teaches MDF is pot/(bet + pot), while Jonathan teaches it is 1 - bet/(pot + bet). They are the same formula, just written in different ways. They will both give you the same answer in heads-up pots.

            I prefer to use the 1 - bet/(bet + pot), because when you figure the MDF for multi-way pots you use a variation of that formula that is not able to be used with the other formula as simply. In a 3 way pot the formula is MDF = 1 - SQRT(bet/[bet + pot]). If you use the Upswing Poker formula for this you have to take an extra step and convert it into the inverse of the formula, which is the formula we started with before you solve.

        • #7
          Londonimp: Thanks, this makes sense!

          jjpregler: I see now that i misread on upswing and thus confused myself. It was pot/(bet+pot) and not bet/(bet+pot).

          Comment


          • #8
            Another question regarding MDF. Am i forcing bb to defend more if i open smaller from sb?
            3bb open = 33% MDF / 2.5bb = 37.5% MDF / 2bb = 42.8% MDF.

            Comment


            • LondonImp
              LondonImp commented
              Editing a comment
              I haven't checked your actual calculations but yes, the smaller the bet the greater MDF will be.

            • jjpregler
              jjpregler commented
              Editing a comment
              No, these numbers do not look right. Did you use an ante? Did you also account that for the SB raising to 3 is only betting 2.5 into a pot of 1.5 without antes or 2.5 with antes.

              So raising to 3 is 37.5 with no antes and 50% with antes.

            • IceFishingEnthusiast
              IceFishingEnthusiast commented
              Editing a comment
              I used the formula from cash game master class, MDF = 1 - bet/(bet + pot). But i see now that it does not apply from sb, but rather from any other position?
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