Simulation True Model Specification
The True Model is the model from which data will be generated. You must specify the PIMs and the Design Matrix for this model, plus the Link Function that links the design matrix to the real parameters.
Three push buttons are provided to select a True Model. The Current push button uses the PIMs and Design Matrix currently defined in memory. If no Design Matrix window is open, the Identity Design Matrix is used by default. The Results push button retrieves the currently-highlighted model from the Results Database. The model name, link function, and variance estimation technique are all set based on the retrieved model. If the Results Browser is not open, the Results push button is not enabled. The File push button (File | Retrieve) does the same thing as the Results push button, except that you are asked to select the file from which the model is to be retrieved, and given a list of models available in the file to select one from. Note that the file you select must have the same data type, number of encounter occasions, number of groups, and number of individual covariates (and with the same names) as the current set of data. A possible advantage of selecting a True Model with the Results and File push buttons is that the parameter estimates are retrieved and used to initialize the Beta parameter values.
Once the True Model has been specified, you can then specify the Beta Values of the True Model, i.e., the values of the Beta parameters that are used to generate the real parameter values from the Design Matrix and the Link Function. A good choice for the link function to be used with an Identity Design Matrix is the Identity link function, because then the values for the Beta parameters are the same as for the real parameters.