Why does it need to be a simulation at all? The model is essentially a geometric random walk with number of trials N and probability of success in each trial P,

Why does it need to be a simulation at all? The model is essentially a geometric random walk with number of trials N and probability of success in each trial P, with P varying. In an additive random walk, the distribution of positions after N time steps is Pascal's triangle with zeros injected every other column and with each row multiplied by one half [1], which is just a shifted binomial distribution (with zeros injected at odd distances on even time steps, and at even distances on odd time steps), with probability mass function of `arw_pmf(k, N, P) = (N choose k) * P^k * (1-P) ^ k - N/2`. For large N, the distribution approaches the normal distribution. In a geometric random walk, the power of the scaling factor takes on the shifted binomial distribution. In this case, the scaling factor is 2, so the probability mass function is `grw_pmf(k, N, P) = 2^arw_pmf(k, N, P)`. Note that this is _not_ a power-law distribution, and therefor will _not_ exhibit a robust 80/20 rule. Even if you convolve this distribution with an input normal distribution over P, as they do in the paper, you would not get a power law distribution. The effect of a change in P, which is used to model talent, is to shift the distribution, but not to greatly affect its shape. The shift is consistent with our expectations that greater "talent" results in higher probability of accumulating more capital, though there is of course an overlap in the distributions of two agents with differing talent. All that being said, I suppose it's possible that the 2D discrete simulation introduces temporal correlations that could alter the population's final capital distribution into a power law distribution. If that's the case, then the power law distribution is due entirely to these temporal correlations, which suggests to me a different insight, namely that the source of inequality is these temporal correlations. In other words, if people who have recently been successful are more likely to continue to be successful, then you will have inequality. Since this seems to describe our world pretty well, perhaps inequality is inevitable? [1]: http://mathworld.wolfram.com/RandomWalk1-Dimensional.html http://mathworld.wolfram.com/RandomWalk1-Dimensional.html