Simulation

R midterms

November 9, 2012 |

Here are my R midterm exams, version A and version B in English (as students are sitting next to one another in the computer rooms), on simulation methods for my undergrad exploratory statistics course. Nothing particularly exciting or innovative! Dedicated ‘Og‘s readers may spot a few Le Monde puzzles ... [Read more...]

Variable probability Bernoulli outcomes – Fast and Slow

November 1, 2012 |

I am working on a project that requires the generation of Bernoulli outcomes. Typically, I would go about this using the built in sample() function like so: This works great and is fast, even for large n. Problem is, I want to generate each sample with its own unique probability. ... [Read more...]

On weather forecasts, Nate Silver, and the politicization of statistical illiteracy

October 30, 2012 |

As you know, we have a thing for statistical literacy here at Simply Stats. So of course this column over at Politico got our attention (via Chris V. and others). The column is an attack on Nate Silver, who has a blog where he tries to predict the outc... [Read more...]

slides for my simulation course

October 18, 2012 |

Similar to last year, I am giving a series of lectures on simulation jointly as a Master course in Paris-Dauphine and as a 3rd year course in ENSAE. The course borrows from both the books Monte Carlo Statistical Methods and from Introduction to Monte Carlo Methods with R, with George ... [Read more...]

ISBA towards higher computing goals [yet another new section!!!]

September 19, 2012 |

Surrounding the great and exciting gathering of Bayesian statisticians in Kyoto last June, several ISBA sections have appeared in the past weeks, as already mentioned on the ‘Og. Along with Anto Mira and Nicolas Chopin (who did most of the organisational work while I was wandering down under!), we discussed ... [Read more...]

Review of “Numerical Methods and Optimization in Finance” by Gilli, Maringer and Schumann

September 12, 2012 |

Previously This book and the associated R package were introduced before. Executive Summary A very nice — and enlightening — discussion of a wide range of topics. Principles The Introduction to the book sets out 5 principles.  This is probably the most important part of the book.  The principles are: We don’t ... [Read more...]

Suicide statistics and the Christchurch earthquake

September 5, 2012 |

Suicide is a tragic and complex problem. This week New Zealand’s Chief Coroner released its annual statistics on suicide, which come with several tables and figures. One of those figures refers to monthly suicides in the Christchurch region (where I … Continue reading → [Read more...]

Why trust some supposed laws of statistical sampling and…

August 15, 2012 |

Why trust some supposed laws of statistical sampling and convergence when you can just test them yourself? If you have a computer with R installed (also recommended: Rstudio) then you can stop dithering about whether these n=1000 studies cited in the n... [Read more...]

Simulation: The modeller’s laboratory

August 10, 2012 |

In his 2004 paper in Trends in Ecology and Evolution, Steven Peck argues: Simulation models can be used to mimic complex systems, but unlike nature, can be manipulated in ways that would be impossible, too costly or unethical to do in natural systems. Simulation can add to theory development and testing, ... [Read more...]

Using discrete-event simulation to simulate hospital processes

July 12, 2012 |

Discrete-event simulation is a very useful tool when it comes to simulating alternative scenario’s for current of future business operations. Let’s take the following case; Patients of an outpatient diabetes clinic are complaining about long waiting times, this seems to have an adverse effect on patient satisfaction and ... [Read more...]

July 10, 2012 |

Simulating Euro 2012

June 11, 2012 |

Why settle for just one realisation of this year’s UEFA Euro when you can let the tournament play out 10,000 times in silico? Since I already had some code lying around from my submission to the Kaggle hosted 2010 Take on the Quants challenge, I figured I’d recycle it for ... [Read more...]

\STATE [algorithmic package]

June 7, 2012 |

I fought with my LαTεX compiler this morning as it did not want to deal with my code: looking on forums for incompatibilities between beamer and algorithmic, and adding all kinds of packages, to no avail. Until I realised one \STATE was missing: (This is connected with my ... [Read more...]

ABC+EL=no D(ata)

May 27, 2012 |

It took us a loooong while [for various and uninteresting reasons] but we finally ended up completing a paper on ABC using empirical likelihood (EL) that was started by me listening to Brunero Liseo’s tutorial in O’Bayes-2011 in Shanghai… Brunero mentioned empirical likelihood as a semi-parametric technique w/... [Read more...]

R, Julia and genome wide selection

April 24, 2012 |

— “You are a pussy” emailed my friend. — “Sensu cat?” I replied. — “No. Sensu chicken” blurbed my now ex-friend. What was this about? He read my post on R, Julia and the shiny new thing, which prompted him … Continue reading → [Read more...]

Insights into Quantile Regression from Arthur Charpentier

April 24, 2012 |

At this Monday’s Montreal R User Group meeting, Arthur Charpentier gave an interesting talk on the subject of quantile regression. One of the main messages I took away from the workshop was that quantile regression can be used to determine if extreme events are becoming more extreme. The example ... [Read more...]

April 14, 2012 |

Typically, regression models in empirical economic research suffer from at least one form of endogeneity bias. The classic example is economic returns to schooling, where researchers want to know how much increased levels of education affect income. Estimation using a simple linear model, regressing income on schooling, alongside a bunch ... [Read more...]

Monty Hall Simulations

March 20, 2012 |

Using R I'm doing a lot of simulations of the classic monty hall-problem and plotting multiple simulations using ggplot2. [Read more...]

π Day Special! Estimating π using Monte Carlo

March 14, 2012 |

In honour of π day (03.14 – can’t wait until 2015~) , I thought I’d share this little script I wrote a while back for an introductory lesson I gave on using Monte Carlo methods for integration. The concept is simple – we can estimate the area of an object which is inside another ... [Read more...]

another X’idated question

February 23, 2012 |

An X’idated reader of Monte Carlo Statistical Methods had trouble with our Example 3.13, the very one our academic book reviewer disliked so much as to “diverse [sic] a 2 star”. The issue is with computing the integral when f is the Student’s t(5) distribution density. In our book, we ... [Read more...]
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