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3. 8. Statistical simulations

Simulations are a means to answer some of the questions raised about the statistical procedures outlined in the above sections of this chapter. The general procedures for the statistical simulations is:
  1. specify the model and choose parameter values, ;
  2. draw a random sample, , of size n from the specified distribution;
  3. perform the statistical procedure - estimate parameters, compute test statistics;
  4. repeat steps 2 and 3 many times to generate distributions of parameter estimates and test statistics;
  5. use these distributions to compute bias or mean squared error (MSE) of parameter estimates or to compare the distribution of test statistics to the theoretical distribution.
Simulations can be performed under a variety of conditions, e.g. different sample sizes or parameter values.

After n simulations are run, the bias of a parameter estimate can be formulated as:

. (3.23)

is the parameter estimate from the ith simulation, and is the true value of the parameter. The MSE of the parameter estimate can be computed as

. (3.24)

After a distribution of test statistics is generated, it can be compared directly to the theoretical distribution. In doing so, the consistency of the two distributions can be determined.


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