Trajectories, random walk and binomial convergence

Statement

A server receives weekly updates for n weeks. Each week there are m independent attackers; each attacker has probability p of succeeding. If at least one succeeds, the week is a breach and counts as -1; if none succeed the week is secure and counts as +1.

\[ \displaystyle q = (1-p)^m . \] \[ \displaystyle K\sim\mathrm{Binom}(n,q), \qquad S_n = 2K - n . \]

Interactive simulator

Instructions
  • Choose parameters and click Run simulation.
  • The app will plot some sample trajectories, the empirical mean, ±sd bands and the theoretical expectation.

Numerical results

Score SnCount (sim)Prob (sim)Prob (theor)

Metrics

Run the simulation to see metrics here (final mean, variance, Chi², KL divergence).

Convergence sweep

Run a quick sweep to observe how Chi² behaves when varying n or the number of simulations.

Interpretation & final notes

The empirical mean approaches E[S_k]=k(2q-1). Increasing sims and n makes the empirical distribution converge to the theoretical one; changing m modifies q and shifts the regime.

References

  1. W. Feller, An Introduction to Probability Theory and Its Applications, Vol.1.
  2. S. Ross, Introduction to Probability Models.
  3. G. Grimmett & D. Stirzaker, Probability and Random Processes.