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  2. Urn problem - Wikipedia

    en.wikipedia.org/wiki/Urn_problem

    Occupancy problem: the distribution of the number of occupied urns after the random assignment of k balls into n urns, related to the coupon collector's problem and birthday problem. Pólya urn: each time a ball of a particular colour is drawn, it is replaced along with an additional ball of the same colour.

  3. Pólya urn model - Wikipedia

    en.wikipedia.org/wiki/Pólya_urn_model

    In the basic Pólya urn model, the experimenter puts x white and y black balls into an urn. At each step, one ball is drawn uniformly at random from the urn, and its color observed; it is then returned in the urn, and an additional ball of the same color is added to the urn. If by random chance, more black balls are drawn than white balls in ...

  4. Beta-binomial distribution - Wikipedia

    en.wikipedia.org/wiki/Beta-binomial_distribution

    Specifically, imagine an urn containing α red balls and β black balls, where random draws are made. If a red ball is observed, then two red balls are returned to the urn. Likewise, if a black ball is drawn, then two black balls are returned to the urn. If this is repeated n times, then the probability of observing x red balls follows a beta ...

  5. Beta negative binomial distribution - Wikipedia

    en.wikipedia.org/wiki/Beta_negative_binomial...

    The random variable of observed draws of blue balls are distributed according to a (,,). Note, at the end of the experiment, the urn always contains the fixed number r + α {\displaystyle r+\alpha } of red balls while containing the random number X + β {\displaystyle X+\beta } blue balls.

  6. Balls into bins problem - Wikipedia

    en.wikipedia.org/wiki/Balls_into_bins_problem

    A powerful balls-into-bins paradigm is the "power of two random choices [2]" where each ball chooses two (or more) random bins and is placed in the lesser-loaded bin. This paradigm has found wide practical applications in shared-memory emulations, efficient hashing schemes, randomized load balancing of tasks on servers, and routing of packets ...

  7. Chain rule (probability) - Wikipedia

    en.wikipedia.org/wiki/Chain_rule_(probability)

    An Urn A has 1 black ball and 2 white balls and another Urn B has 1 black ball and 3 white balls. Suppose we pick an urn at random and then select a ball from that urn.

  8. Dirichlet distribution - Wikipedia

    en.wikipedia.org/wiki/Dirichlet_distribution

    Initially, the urn contains α 1 balls of color 1, α 2 balls of color 2, and so on. Now perform N draws from the urn, where after each draw, the ball is placed back into the urn with an additional ball of the same color. In the limit as N approaches infinity, the proportions of different colored balls in the urn will be distributed as Dir(α 1 ...

  9. Joint probability distribution - Wikipedia

    en.wikipedia.org/wiki/Joint_probability_distribution

    Let and be discrete random variables associated with the outcomes of the draw from the first urn and second urn respectively. The probability of drawing a red ball from either of the urns is ⁠ 2 / 3 ⁠, and the probability of drawing a blue ball is ⁠ 1 / 3 ⁠. The joint probability distribution is presented in the following table: