Maximum Likelihood MT (maxlikmt)
==================================
A maximum likelihood package for **GAUSS**.
Description
----------------
MaxlikMT provides a suite of flexible, efficient and trusted tools for the solution of the maximum likelihood problem with bounds on the parameters.
Installation
--------------
Please `contact us `_ with to request pricing and installation information.
If you already own **maxlikMT**, you can use the `GAUSS Package Manager `_ to install maxlikMT as well.
Requires GAUSS/GAUSS Light version 17 or higher.
Key Features
------------------------------
Statistical Inference
+++++++++++++++++++++++++++++++
**maxlikmt** provides methods for statistical inference of weighted or unweighted, bounded or unbounded maximum likelihood models.
* Inverted Hessian covariance matrix
* Heteroskedastic-consistent covariance matrix
* Wald confidence limits
* Likelihood ratio statistics
* Bootstrap
* Likelihood profile and Profile ‘t’ traces
Descent methods
+++++++++++++++++++++++++++++++
* BFGS (Broyden, Fletcher, Goldfarb and Powell)
* BHHH (Berndt, Hall, Hall, and Hausman)
* DFP (Davidon, Fletcher and Powell)
* Newton
Line search methods
+++++++++++++++++++++++++++++++
* STEPBT
* Brent’s method
* Half
* Strong Wolfe’s conditions
Advantages
--------------------------------
Flexible
+++++++++++++++++
* Bounded parameters.
* Specify fixed and free parameters.
* Dynamic algorithm switching.
* Compute all, a subset, or none of the derivatives numerically.
* Easily pass data other than the model parameters as extra input arguments. New!
* Methods to simply create matrices needed for log-likelihood computation from subsets of the parameters.
Efficient
+++++++++++++++
* Threaded and thread-safe.
* Option to avoid computations that are the same for the log-likelihood function and derivatives.
* The tremendous speed of user-defined procedures in **GAUSS** speeds up your estimation.
Trusted
+++++++++++
For more than 30 years, leading researchers have trusted the efficient and numerically sound code in the **GAUSS** maximum likelihood estimation tools to keep them at the forefront of their fields.
Available Optimization Controls
--------------------------------
Optimization controls are set to default values that few users ever need to change. However, **maxlikmt** is fully customizable and the flexible optimization options can be a great help when tackling more difficult problems.
Control Options
+++++++++++++++++++++++++++++++
.. list-table::
:widths: auto
* - Parameter bounds
- Simple parameter bounds of the type: lower_bd ≤ x_i ≤ upper_bd.
* - Descent algorithms
- BFGS, DFP, Newton, and BHHH.
* - Algorithm switching
- Specify descent algorithms to switch between based upon the number of elapsed iterations, a minimum change in the objective function, or line search step size.
* - Weights
- Observation weights.
* - Covariance matrix type
- Compute a ML covariance matrix, a QML covariance matrix, or none.
* - Alpha
- Probability level for statistical tests.
* - Line search method
- STEPBT (quadratic and cubic curve fit), Brent’s method, BHHHStep, half-step or Strong Wolfe’s Conditions.
* - Active parameters
- Control which parameters are active (to be estimated) and which should be fixed to their start value.
* - Gradient Method
- Either compute an analytical gradient, or have **maxlikmt** compute a numerical gradient using the forward, central, or backwards difference method.
* - Hessian Method
- Either compute an analytical Hessian, or have **maxlikmt** compute a numerical Hessian using the forward, central, or backwards difference method.
* - Gradient check
- Compares the analytical gradient computed by the user-supplied function with the numerical gradient to check the analytical gradient for correctness.
* - Random seed
- Starting seed value used by the random line search method to allow for repeatable code.
* - Print output
- Controls whether (or how often) iteration output is printed and whether a final report is printed.
* - Gradient step
- Advanced feature: Controls the increment size for computing the step size for numerical first and second derivatives.
* - Random search radius
- The radius of the random search if attempted.
* - Maximum iterations
- Maximum iterations to converge.
* - Maximum elapsed time
- Maximum number of minutes to converge.
* - Maximum random search attempts
- Maximum allowed number of random line search attempts.
* - Convergence tolerance
- Convergence is achieved when the direction vector changes less than this amount.
.. toctree::
:maxdepth: 2
:hidden:
:caption: Maximum Likelihood Documents
user-guide
command-reference
mlmt-examples