**Timely Portfolio**, and kindly contributed to R-bloggers)

I did not intend for this to be a multi-part series, but after some clear thinking at the beach over the weekend, I decided that it needed some more analysis. For those of you that read the article or know Mahalanobis distance, the measure I presented in my post Great FAJ Article on Statistical Measure of Financial Turbulence was a derivative of actual Mahalanobis distance. To close the gap between the actual calculation and my measure, I thought I should show both calculations.

From TimelyPortfolio |

From TimelyPortfolio |

The Mahalanobis calculation here is based on the entire dataset. Of course, we do not have the luxury of hindsight in trading, so I think my real-time measure works well as displayed by the system shown in the first post.

R code:

require(quantmod)

require(PerformanceAnalytics)

#get data from St. Louis Federal Reserve (FRED)

getSymbols(“GS20″,src=”FRED”) #load 20yTreasury; 20y has gap 86-93; 30y has gap in early 2000s

getSymbols(“GS30″,src=”FRED”) #load 30yTreasury to fill 20y gap 86-93

#getSymbols(“BAA”,src=”FRED”) #load BAA

getSymbols(“SP500″,src=”FRED”) #load SP500

#get CRB data from a csv file

CRB<-as.xts(read.csv(“crb.csv”,row.names=1))[,1]

#fill 20y gap from discontinued 20y Treasuries with 30y

GS20[“1987-01::1993-09″]<-GS30[“1987-01::1993-09″]

#do a little manipulation to get the data lined up on monthly basis

SP500<-to.monthly(SP500)[,4]

#get monthly format to yyyy-mm-dd with the first day of the month

index(SP500)<-as.Date(index(SP500))

#my CRB data is end of month; could change but more fun to do in R

CRB<-to.monthly(CRB)[,4]

index(CRB)<-as.Date(index(CRB))

#let’s merge all this into one xts object; CRB starts latest in 1956

assets<-na.omit(merge(GS20,SP500,CRB))

#use ROC for SP500 and CRB and momentum for yield data

assetROC<-na.omit(merge(momentum(assets[,1])/100,ROC(assets[,2:3],type=”discrete”)))

#get Covariances and multiply to by 100000 for 20y to sp500 and crb and 1000 for sp500 to crb to standardize

#don’t like this manual intervention; next post will use correlation instead

assetCovar<-runCov(assetROC[,1],assetROC[,2],n=2)*100000+runCov(assetROC[,1],assetROC[,3],n=2)*100000+runCov(assetROC[,2],assetROC[,3],n=2)*1000

assetROCSum<-assetROC[,1]+assetROC[,2]+assetROC[,3]

turbulence<-abs(assetCovar*assetROCSum)

Sx <- cov(assetROC)

mahalanobisturbulence <- mahalanobis(assetROC, colMeans(assetROC), Sx)

mahalanobisturbulence<-as.xts(cbind(mahalanobisturbulence))

turbulencecompare<-merge(mahalanobisturbulence,turbulence)

colnames(turbulencecompare)<-c(“Mahalanobis”,”MyEstimate”)

chart.TimeSeries(turbulencecompare,main=”Mahalanobis Distance Compared to My Measure”,

colorset=c(“cadetblue”,”darkolivegreen3″),legend.loc=”topleft”)

chart.Correlation(turbulencecompare)

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**Timely Portfolio**.

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