# Tag Info

### Usage of Random forests in Quantitative analysis of stocks

Recently I attended a presentation by the first author of the following paper who gave us quite a creative and illuminating (kind of meta-)use of random forests in Quant Finance: All that Glitters Is ...
Accepted

### Does Chan use the wrong state transition model in his Kalman filter code?

In addition to getting the right transition model for the Kalman filter, the main obstacle to optimizing filter performance is to implement an optimal initialization. I use an iterative approach to ...
Accepted

### What is the total correlation between assets in a portfolio?

This is indeed an interesting question. According to this website, a paper by Goldman Sachs [Tierens and Anadu (2004)] proposes three alternative methods for estimating average stock correlations: ...
Accepted

### statistical arbitrage vs factor trading

1) Why would you trade the error on the residual instead of creating a long/short factor model and trade expected returns? I would posit that the biggest reason people do this is for orthogonality of ...

### Implied Volatility of stock on Think or Swim

What they gave you is Newton's formula. If you have a function $f(x)$ then you can find the value $x_0$ such that $f(x_0) = 0$ by this method. It uses the derivative $f'$ which in your case is the ...

### What is the total correlation between assets in a portfolio?

I just want to add to vonjd's answer some info on the comparison of the 3 methods. This is too big for a comment so I'm posting as a separate answer but please upvote his answer, not mine. Do the ...

### What color financial time series are there?

Bonus question: Does anyone know how to play/hear a (financial) time series recorded as a pandas series, dataframe, python list, numpy array, csv/txt file,... ? This is kind of fun and has practical ...

### Quantitative finance for physicists

Physicists typically know PDEs but not stochastic calculus I have a masters in physics, so have a reasonable idea of the usual skillsets a physicist will know (at least at undergraduate level), and ...
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### Is it always better to use the entire distribution of a financial returns series, not just $\mu$ and $\sigma$?

It depends. For example, if you're doing option pricing in the log normal world returns are completely described by the mean and standard deviation. If you add jumps, you would also need to ...
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### Fat tailed can be estimated through a t-distributions?

B is the correct choice. I honestly would wish multiple choice would not even exist. It is the worst way of testing knowledge in my opinion. Without knowing the details of what was taught, I would say ...
Accepted

### How to identify daily returns as an unusual daily return given a dataset

Given you have your returns $$r_t = \frac{P_t - P_{t-1}}{P_{t-1}}$$ you can compute the absolute z-score as $$Z_t = \frac{r_t-\mu(r)}{\sigma(r)}$$ where $\mu(r)$ and $\sigma(r)$ are the mean and ...

### What are the advantages of financial modelling in R?

Some advantages of R over Excel: R is a scripting language, which allows to record a data manipulation script once and reuse it multiple times. R, as a [scripting] programming language is much more ...

### Where can I find ideas for strategies?

There are lots of different sources out there where you can find various quantitative strategies. Usually, different blog aggregators like https://www.r-bloggers.com post on their websites ...

### Central limit theorem and normality assumption of asset return distribution

No. I just published a paper on this. If return is defined as $$r_t=\frac{p_{t+1}q_{t+1}}{p_tq_t},$$ and since returns are not data while prices and volumes are, then it follows that the ...

### Utility functions, are they used in the real world by hedge funds, banks, etc?

In the Black Scholes (1973) model, the stock price is assumed to follow a geometric Brownian motion $\mathrm{d}S_t=S_t\mu \mathrm{d}t + S_t \sigma \mathrm{d}W_t$. If you solve the SDE, $(S_t)$ is log-...