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PROBIT Procedure


The PROBIT procedure calculates maximum likelihood estimates of regression parameters and the natural (or threshold) response rate for quantal response data from biological assays or other discrete event data. This includes probit, logit, ordinal logistic, and extreme value (or gompit) regression models. The following are highlights of the PROBIT procedure's features:

  • performs chi-square tests for model effects that test Type I, Type II, or Type III hypotheses
  • provides amechanism for performing custom hypothesis tests
  • produces a display of the fitted model and provides options for changing and enhancing the displays
  • plots the predicted cumulative distribution function (CDF) of the multinomial response variable as a function of a single continuous independent variable (dose variable)
  • plots the inverse of the predicted probability (IPP) against a single continuous variable (dose variable) for the binomial model
  • plots the linear predictor (LPRED) x'b against a single continuous variable (dose variable) for either the binomial model or the multinomial model
  • plots the predicted probability against a single continuous variable (dose variable) for both the binomial model and the multinomial model
  • computes and compares least squares means (LS-means) of fixed effects
  • provides custom hypothesis tests among least squares means
  • performs a partitioned analysis of the LS-means for an interaction
  • perform weighted estimation
  • enables you to save the context and results of the statistical analysis in an item store, which can be processed with the PLM procedure
  • creates a SAS data set that contains the parameter estimates and their estimated covariances
  • creates a SAS data set that contains the input data, the fitted probabilities, the linear prediction and the estimate of its standard error
  • creates a SAS data set that corresponds to any output table
  • performs BY group processing, which enables you to obtain separate analyses on grouped observations
  • automatically creates graphs by using ODS Graphics

For further details see the SAS/STAT User's Guide: The PROBIT Procedure
( PDF | HTML )

Examples