Difference between revisions of "Expectation Maximization"

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Expectation Maximization is a technique to infer the parameters of  a statistical model and the underlying intuition is that an optimal parametrized statistical model will give a highest probability to the training data on which it is trained. It consists of the expectation or E- step in which the log likelihood probability is calculated based on the current estimate of the parameters and the hidden (latent) variables and a maximization or M-step in which the value of the parameters is updated to increase the maximum value of the likelihood function. EM can be used to discover a local maxima for the log-likelihood function.
 
 
In statistics, an expectation-maximization (EM) algorithm is a method for finding maximum likelihood or maximum a posteriori (MAP) estimates of parameters in statistical models, where the model depends on unobserved latent variables. EM is an iterative method which alternates between performing an expectation (E) step, which computes the expectation of the log-likelihood evaluated using the current estimate for the latent variables, and a maximization (M) step, which computes parameters maximizing the expected log-likelihood found on the E step.
 
  
 
[http://en.wikipedia.org/wiki/Expectation-maximization_algorithm External link]
 
[http://en.wikipedia.org/wiki/Expectation-maximization_algorithm External link]

Revision as of 01:58, 1 April 2011

Expectation Maximization is a technique to infer the parameters of a statistical model and the underlying intuition is that an optimal parametrized statistical model will give a highest probability to the training data on which it is trained. It consists of the expectation or E- step in which the log likelihood probability is calculated based on the current estimate of the parameters and the hidden (latent) variables and a maximization or M-step in which the value of the parameters is updated to increase the maximum value of the likelihood function. EM can be used to discover a local maxima for the log-likelihood function.

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