Machine Learning Math Series (4): Parameter Estimation

main content:

Point estimate:

  moment estimation

  maximum likelihood estimation

  Criteria for Point Estimation

Interval estimate:

  confidence interval

 

Symbol Description:

1 Parameter estimation problem

2 point estimate

2.1 Moment Estimation

The basic idea of ​​the moment estimation method is to use the sample moment to estimate the population distribution moment according to the law of large numbers.

The parameters are then estimated using the relationship between the population moments and the parameters.

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Fundamentals of Moment Estimation: The Law of Large Numbers

Example 1: Parameter estimation of a two-point distribution

Example 2: Parameter estimation for a normal distribution

2.2 Maximum Likelihood Estimation

Given the distribution and unknown parameters of a random variable, compute the likelihood function using the observed samples.

The parameter that maximizes the likelihood function is chosen as the parameter estimator.

The basic principle of the maximum likelihood function: maximize the likelihood function.

Example: Parameter estimation for a normal distribution

2.3 Criteria for point estimation

2.4 Point Estimation: Consistency

Consistency is the most basic requirement, the consistency of moment estimation is guaranteed by the law of large numbers, and the consistency of maximum likelihood estimation is also implicitly guaranteed by the law of large numbers.

2.5 Point Estimation: Unbiased

Any parameter estimate that satisfies consistency will converge to the true value of the parameter when the sample tends to infinity. But in the case of finite samples, the expectation of this estimate may not always be equal to the true value of the parameter.

2.6 Point Estimation: Validity

example:

2.7 Point Estimation: Asymptotic Normality

Asymptotic normal This involves some knowledge of matrices, especially the asymptotic normal properties of maximum likelihood estimation.

2.8 Interval Estimation: Confidence Intervals

 

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