Tagged Questions
-4
votes
0answers
60 views
How could covariance help with pattern prediction? [closed]
Could someone give me a "high-level" explanation how I could use the technique of covariance to implement a pattern recognition technique?
I have used autocorrelation in the past for detecting ...
3
votes
0answers
81 views
Stress testing covariance
Going one level beyond stressed scenarios, to parameters e.g. for a VaR measure: what are the most common approaches for stressing a covariance/correlation matrix, especially taking portfolio exposure ...
3
votes
1answer
68 views
How can I evaluate how poor a fit a parametric VaR result would be for a given holding?
I'm currently working on an application that, among other things, computes a one-day parametric VaR for security positions. I understand that the parametric method of computing VaR is a poor fit for ...
4
votes
2answers
192 views
Most natural generalization of covariance/correlation to model dependence of extreme events
One of the most serious shortcomings of covariance/correlation are the assumptions of linearity and normality.
What is the most natural generalization of these measures of dependence when you want to ...
2
votes
1answer
94 views
Combining covariances?
Consider an economy with assets with return processes $A$, $B$, $C$, $D$. Consider a weighted index with return process $I=aA + bB + cC + dD$ where $a,b,c,d$ are coefficients, and $a+b+c+d = 1$.
...
6
votes
3answers
258 views
age-sensitive correlation measurements in finances
When it comes to comparing returns or prices of instruments like stocks/ETFs, are there any well-established formulas, or ones in common use, that place stronger emphasis on recent correlations more ...
3
votes
3answers
422 views
portfolio diversification tester
Are there any online tools (optionally with developer API, to spare me the scraping) that given an existing portfolio, calculate how well a new candidate position would score to increase combined ...
11
votes
1answer
664 views
Cleansing covariance matrices via Random matrix theory
I am exploring de-noising and cleansing of covariance matrices via Random Matrix Theory. RMT is a competitor to shrinkage methods of covariance estimation. There are various methods expressed usually ...
13
votes
3answers
3k views
What is the best way to “fix” a covariance matrix that is not positive semi-definite?
I have a sample covariance matrix of S&P 500 security returns where the smallest k-th eigenvalues are negative and quite small (reflecting noise and some high correlations in the matrix).
I am ...
23
votes
5answers
2k views
How do I graphically represent the evolution of a covariance matrix over time?
I am working with a set of covariance matrices evaluated at various points in time over some history. Each covariance matrix is $N\times N$ for $N$ financial time-series over $T$ periods. I would ...
9
votes
1answer
341 views
How to estimate the covariance of an index with a basket of stocks?
What would be an ideal way to estimate the covariance of an index with a basket of stocks? For example, should I use one-tail ANOVA test or an individual stock & index F-test?
