Articles by Pat

Reminiscences of R in Finance 2016

May 29, 2016 | Pat

When I announced R in Finance 2016 I talked about 2 days of conference and 50 speakers.  I missed out the 3 days of sleep deprivation. But a pleasant 3 days of sleep deprivation it was — seeing old friends and making new ones. I’m not sure that Mother Mary believed me that in our … ... [Read more...]

R in Finance and other events

April 11, 2016 | Pat

Highlighted R in Finance 2016 May 20-21, Chicago. 2 days, limited space, 50 speakers, including: Pat Burns on “Some Linguistics of Quantitative Finance” Abstract: How can the abstract be written for a talk with an ambiguous and possibly misleading title without itself being vague and misleading? I don’t know, but perhaps: A ...
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Effective risk management with R

September 21, 2014 | Pat

Conference The first EARL Conference (Effective Applications of the R Language) was held 2014 September 15-17 in London. Talk My talk was “Effective risk management with R” (annotated slides). Instability hypothesis When I was preparing for the talk, one of my ideas was to show the Google trend for searches for ... [Read more...]

EARL and other upcoming events

July 28, 2014 | Pat

Highlighted EARL As in “Effective Applications of the R Language”. 2014 September 15-17, London. Somehow they gave higher billing to Ben Goldacre than to Pat Burns.  If Obama were coming, they’d probably bill him above me too — and what does he know about R?  In spite of that little glitch, ...
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BurStFin R package version 1.02 released

March 16, 2014 | Pat

More efficiency and an additional function in the new version on CRAN. Variance estimation The major functionality in the package is variance estimation: Ledoit-Wolf shrinkage via var.shrink.eqcor statistical factor model (principal components) via factor.model.stat There have been a number of previous blog posts on both factor ... [Read more...]

A complicated answer to a simple correlation question

February 9, 2014 | Pat

A data analysis surprise party. Simple question If I have correlation matrices each estimated with a month of daily returns, how much worse is the average of six of those compared to the estimate with six months of daily data? Expected answer Do a statistical bootstrap with the returns and ... [Read more...]

What is volatility?

January 19, 2014 | Pat

Some facts and some speculation. Definition Volatility is the annualized standard deviation of returns — it is often expressed in percent. A volatility of 20 means that there is about a one-third probability that an asset’s price a year from now will have fallen or risen by more than 20% from its ... [Read more...]

garch models caught in the spotlight

January 13, 2014 | Pat

An attempt to clarify the basics. Previously There have been several posts about garch.  In particular: A practical introduction to garch modeling The components garch model in the rugarch package Genesis A reader emailed me because he was confused about the workings of garch in general, and simulation with the ...
[Read more...]

S&P that might have been

January 6, 2014 | Pat

The S&P 500 returned 29.6% in 2013.  How might that have varied? S&P weights There are many features that could vary — here we will keep the same constituents (almost) and weights with similar sizes but that are randomly assigned rather than based on market capitalization. That is, we want the large ... [Read more...]

Blog year 2013 in review

December 30, 2013 | Pat

Highlights of the blog over the past year. Most popular posts The posts with the most hits during the year. A practical introduction to garch modeling (posted in 2012) A tale of two returns (posted in 2010) The top 7 portfolio optimization problems (posted in 2012) The number 1 novice quant mistake (posted in 2011) On ... [Read more...]

Further adventures with higher moments

December 23, 2013 | Pat

Additional views of the stability of skewness and kurtosis of equity portfolios. Previously A post called “Four moments of portfolios” introduced the idea of looking at the stability of the mean, variance, skewness and kurtosis of portfolios through time. That post gave birth to a presentation at the London Quant ... [Read more...]

Historical Value at Risk versus historical Expected Shortfall

November 18, 2013 | Pat

Comparing the behavior of the two on the S&P 500. Previously There have been a few posts about Value at Risk (VaR) and Expected Shortfall (ES) including an introduction to Value at Risk and Expected Shortfall. Data and model The underlying data are daily returns for the S&P 500 from 1950 ... [Read more...]

Quant finance blogs

October 22, 2013 | Pat

What I’ve learned from updating the blogroll. New entries The easy option is to go to The Whole Street which aggregates lots of quant finance blogs. Somehow Bookstaber missed out being on the blogroll before — definitely an oversight. Timely Portfolio was another that I was surprised wasn’t already ...
[Read more...]

Four moments of portfolios

October 14, 2013 | Pat

What good are the skewness and kurtosis of portfolios? Previously The post “Cross-sectional skewness and kurtosis: stocks and portfolios” looked at skewness and kurtosis in portfolios.  The key difference between that post and this one is what distribution is being looked at. The previous post specified a single time and ... [Read more...]

The look of verifying data

October 7, 2013 | Pat

Get data that fit before you fit data. Why verify? Garbage in, garbage out. How to verify The example data used here is daily (adjusted) prices of stocks.  By some magic that I’m yet to fathom, market data can be wondrously wrong even without the benefit of the possibility ... [Read more...]

Changeability of Value at Risk estimators

August 26, 2013 | Pat

How does Value at Risk change through time for the same portfolio? Previously There has been a number of posts on Value at Risk, including a basic introduction to Value at Risk and Expected Shortfall. The components garch model was also described. Issue The historical method for Value at Risk ... [Read more...]

The scaling of Expected Shortfall

June 16, 2013 | Pat

Getting Expected Shortfall given the standard deviation or Value at Risk. Previously There have been a few posts about Value at Risk and Expected Shortfall. Properties of the stable distribution were discussed. Scaling One way of thinking of Expected Shortfall is that it is just some number times the standard ... [Read more...]

Introduction to stable distributions for finance

June 10, 2013 | Pat

A few basics about the stable distribution. Previously “The distribution of financial returns made simple” satirized ideas about the statistical distribution of returns, including the stable distribution. Origin As “A tale of two returns” points out, the log return of a long period of time is the sum of the ... [Read more...]

Value at Risk and Expected Shortfall, and other upcoming events

June 4, 2013 | Pat

Highlighted Value at Risk and Expected Shortfall A two-day course exploring Value at Risk and Expected Shortfall, and their role in risk management. 2013 June 25 & 26, London. Lead by Patrick Burns. Details at the CFP Events site. New Events Thalesians — San Francisco 2013 June 5. Jesse Davis on “Risk Model Imposed Manager-to-Manager … Continue reading →
[Read more...]

Value at Risk with exponential smoothing

May 28, 2013 | Pat

More accurate than historical, simpler than garch. Previously We’ve discussed exponential smoothing in “Exponential decay models”. The same portfolios were submitted to the same sort of analysis in “A look at historical Value at Risk”. Issue Markets experience volatility clustering.  As the previous post makes clear, historical VaR suffers ... [Read more...]
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