Suppose that you want to estimate the parameters of a model and you have more than one set of moment conditions available.
For example, consider the case that you have n, normally distributed observation and you want to estimate the mean.
In addition, let's suppose that you want to use two moment conditions, so that you can have an overidentified model. Recall that a normally distributed variable is symmetric, meaning that mean = median, and curtosis = skewness = 0. Which of the following sets of moments will perform the best?
Set 1: Sample mean, and variance
Set 2: Sample median, and variance
Set 3: Sample mean, and skewness
Set 4: Sample median, and skewness
Set 5: Sample mean, and kurtosis
Set 6: Sample median, and kurtosis
In this case, you can estimate the mean using each possible set of moment conditions and then calculate a moment selection criterion to select the set that performs the best. The program currently supports two type of selection criteria (select the one you want help on): MSC and the RMSC.
Due to the similarity of the two procedures, they are explained simultaneously below.
To use the MSC, click on the Testing drop down menu and select the MSC entry; to use the RMSC, select the RMSC entry.
What you should see in each case will be siimilar to the following
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Moment Selection Criterion |
Relevance Moment Selection Criterion |
The listbox that appears on the top of both windows will not, in general, be empty (actually, it must be non-empty in order to perform the tests).
This listbox will automatically read and list the name of all variables that exist in your workspace.
For example, suppose that you used the GMM-GUI to perform the estimation that we talked about in the example above, and you saved the output using the names set1, set2,..., set6. In this case, opening the MSC or RMSC windows will result to:
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Moment Selection Criterion |
Relevance Moment Selection Criterion |
As you can see, the listbox displays the name of the variables that you have saved in your workspace. With this example in mind, let's continue defining the way these windows work.