Applied Stochastic Processes
From the [course syllabus]:
Stochastic processes are indexed collections of random variables used to describe phenomena in which a dependence structure arises from evolution across time (or space). Markov processes, in particular, are stochastic processes in which dependence is local: given the current state (or values on a separating boundary), the future (outside the boundary) is conditionally independent of the past (or interior history). Markov processes have rich applications in epidemiology, finance, biology, social science, engineering, chemistry, and beyond, and they are also important in statistics. In particular, Markov chain Monte Carlo (MCMC) methods are central to modern Bayesian statistics as a means to approximate complex posterior distributions for Bayesian inference via simulation. This course is a graduate-level introduction to Markov processes and Markov chains, covering four key areas: discrete-time models, continuous-time models, MCMC, and, briefly, Brownian motion and Gaussian processes. Students can expect to learn core concepts and probabilistic language for describing Markov processes, gain exposure to common models and estimation methods, and explore applications.
Instructor: Trevor Ruiz (he/him) [email]
Class meetings: 10:10am–12:00pm MW in 10-124
Office hours: MW 1:00pm–2:30pm and [by appointment] in 25-236 or via Zoom; drop-ins are welcome but appointments are recommended/appreciated.
Week 1 (1/5)
Monday: introduction to Markov chains
- [hw1] exercises 2.1, 2.9, 2.10, 2.16, 2.27 (copy of gamblersruin.R), due Monday 1/12
- [reading] syllabus; 1.2, 2.1
- [lecture notes]
Wednesday: transition probabilities
- [reading] 2.2, 2.3
- [R script]
- [lecture notes]
Week 2 (1/12)
Monday: limiting and stationary distributions
- [hw2] exercises 3.7, 3.8, 3.14a-b,
3.22,3.10, 3.63 (copy of utilities.R), due Tuesday 1/20 - [reading] 2.4, 3.1,
3.2 - [R script] exploring limits
- [lecture notes]
Wednesday: finding stationary distributions
- [reading]
3.33.2 - [R script]
- [lecture notes]
Week 3 (1/20)
MLK Day observed; Tuesday follows Monday schedule
Tuesday: recurrence, transience, and periodicity
- [hw3] exercises 3.23, 3.29, 3.52, 3.54, 3.66; optionally, 3.64
- [reading] 3.3, 3.5
- [lecture notes]
Wednesday: limit theorem for finite Markov chains
- [reading] 3.6, 3.8, 3.10
- [R script] random walks on \(\mathbb{Z}^d\)
- [lecture notes]
Week 4 (1/26)
Monday: likelihood estimation
- [reading] Guttorp, P. (1995). Stochastic modeling of scientific data. Chapter 2, section 2.7. [pdf]
- [reference] Anderson, T. W., & Goodman, L. A. (1957). Statistical inference about Markov chains. The Annals of Mathematical Statistics, 28(1); 89-110. [pdf]
- [R script] weather in SLO
- [lecture notes]
Wednesday: Bayesian estimation
- [R script] fitting random walks to GeoLife trajectories (requires data download from Microsoft)
- [R script] Dirichlet smoothing with NYC taxi data (requires data download, link in script)
- [lecture notes]
Week 5 (2/2)
Groundhog Day not observed (but see data on Phil’s predictions and some simple models)
Monday: mini-project 1
Wednesday: midterm
Week 6 (2/9)
Monday: Metropolis-Hastings algorithm
- [hw4] 5.7, 5.8, 5.19, 5.18, and your in-class example
5.17 and add a part (c) identify the likelihood and prior that produce this posterior in a Bayesian framework - [reading] 5.1, 5.2
- [R script] uncertainty quantification
- [R script] Dirichlet-multinomial MCMC
- [lecture notes]
Wednesday: random walk Metropolis; Gibbs sampler
- [reading]
5.3 - [R script] implementing Metropolis-Hastings
- [lecture notes]
Week 7 (2/17)
President’s Day observed
Wednesday: Gibbs sampler
Week 8 (2/23)
Monday: homogeneous Poisson processes
- [hw6] 6.12, 6.23, 6.35, 6.41, 6.42, 6.43
- [reading] 6.1, 6.2, 6.5
- [lecture notes]
Wednesday: spatial and nonhomogeneous Poisson processes
- [reading] 6.4, 6.6, 6.7
- [R script] earthquake data
- [lecture notes]
Week 9 (3/2)
Monday: estimation of nonhomogeneous intensity; point processes
- [R script] estimating a nonhomogeneous Poisson spatial intensity
- [R script] fitting a Hawkes process model
- [lecture notes]
Wednesday: mini-project 2
Week 10 (3/9)
Monday: introduction to Brownian motion (asynch; no class meeting)
- [reading] 8.1-8.2
- [notebook] Brownian motion as a limit of random walks
Wednesday: Brownian motion and applications
- [reading] 8.3-8.5
- [R script] simulating Brownian motion
- [R script] modeling animal movement
- [lecture notes]