Integrate mixture of multivariate normal distributions

In summary, the person is asking for advice on how to compute the integral for a mixture of multivariate normal distributions. They have already done it numerically but are looking for an analytic solution. Another person suggests using the linear property of the integral and partitioning it based on the linear nature of the mixture model. However, the person is having trouble with the individual integrals for each component. It is mentioned that an analytic solution may not be possible and that special functions or series expansions may be needed.
  • #1
Neddie
2
0
I have a mixture of multivariate normal distributions, and I want to compute the integral with the first element of the input vector varying between specified limits, and the other elements varying from -infinity to +infinity. See attached pdf for equations. I've done it numerically but would like an analytic solution. Any advice? Thanks!
 

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  • #2
Hey Neddie and welcome to the forums.

I'm not an expert by any means so take this with a large grain of salt but since your mixture function is linear, can you not just use the linear property of the integral?

That is given Integral over space X f(X) + g(X) = Integral over space X f(X) + Integral over space X g(X), if you partition your integral using each component of the linear sum could you not just separate the integral accordingly and use the normal rules to evaluate each piece by itself which then can be combined?

I don't know if this is possible but it seems that at a glance you could partition the integral based on the linear nature of your mixture model but I am probably missing something here.
 
  • #3
Thanks chiro. You're quite right -- the integral over the mixture is trivially the sum of the integrals over each mixture component. It's actually those integrals I'm having trouble with.
 
  • #4
To my knowledge, I don't think you can actually get an analytic expression for the normal in both univariate or multivariate unless you use some special function of some sort that is a series expansion.

For the standard normal we use tables and my guess (although may be wrong) is that the generalized expression just gets more ugly and not any better.
 

1. What is a multivariate normal distribution?

A multivariate normal distribution is a type of probability distribution that is characterized by multiple variables that are normally distributed. It is often used to model data with multiple variables that are correlated with each other.

2. How do you integrate a mixture of multivariate normal distributions?

The integration of a mixture of multivariate normal distributions can be done using numerical methods such as Monte Carlo integration or Gaussian quadrature. These methods involve approximating the integral using a series of calculations and can be implemented using software or programming languages such as R or Python.

3. What are the benefits of using a mixture of multivariate normal distributions?

Using a mixture of multivariate normal distributions allows for more flexibility in modeling complex data. It can capture the correlations between variables and can also handle data with outliers or non-normal distributions. Additionally, it can provide more accurate predictions compared to using a single multivariate normal distribution.

4. What are the limitations of using a mixture of multivariate normal distributions?

One limitation of using a mixture of multivariate normal distributions is that it can be computationally intensive, especially with a large number of variables. It also assumes that the data is normally distributed, which may not always be the case in real-world scenarios. Additionally, choosing the appropriate number and proportions of the mixture components can be challenging and may require some trial and error.

5. How can a mixture of multivariate normal distributions be applied in real-world scenarios?

A mixture of multivariate normal distributions can be applied in a variety of fields, such as finance, biology, and social sciences. It can be used for data analysis, forecasting, and risk assessment. For example, in finance, it can be used to model stock returns and estimate the risk of a portfolio. In biology, it can be used to model gene expression data and identify patterns or clusters. In social sciences, it can be used to model survey data and identify underlying factors or trends.

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