# The HPQLIM Procedure

The HPQLIM (high-performance qualitative and limited dependent variable model) procedure is a high-performance version of the QLIM procedure in SAS/ETS^{®} software. Like the QLIM procedure,
the HPQLIM procedures analyzes univariate limited dependent variable models in which dependent variables are observed only in a limited range of values.

Unlike the QLIM procedure, which can be run only on an individual workstation, the HPQLIM procedure takes advantage of a computing environment that enables it to distribute the optimization task among
one or more nodes. In addition, each node can use one or more threads to carry out the optimization on its subset of the data. When several nodes are used, with each node using several threads to carry
out its part of the work, the result is a highly parallel computation that provides a dramatic gain in performance.

The HPQLIM procedure is similar in use to other SAS procedures that support regression or simultaneous equations models. For example, the standard model with censoring or truncation is estimated
by specifying the endogenous variable to be truncated or censored. When the data are limited by specific values or variables, the limits of the dependent variable can be specified in the CENSORED or
TRUNCATED option in the ENDOGENOUS or MODEL statement.

The HPQLIM procedure estimates the parameters of a regression model by maximum likelihood techniques and supports the following models:

- linear regression models with heteroscedasticity
- Tobit models (censored and truncated) with heteroscedasticity
- stochastic frontier production and cost models

## Documentation

For further details, see the *SAS/ETS*^{®} User's Guide: High Performance Procedures

## Examples