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# Individual parameters

In the mlxtran model, the following parameters are recognized as individual parameters:

• Only the [LONGITUDINAL] block is present: all parameters of the input list, except those defined as regressors.
• Both the [LONGITUDINAL] and [INDIVIDUAL] blocks are present: parameters defined in the DEFINITION section of the [INDIVIDUAL] block.

Individual parameters can be used in the tab “Exploration” and “Simulation”. An individual parameter definition is either a vector, which has one value per parameter, or a table, where each line correspond to a value of a different individual.

Demo projects: 3.4. individual parameters

#### New individual parameters elements

After loading a model, Simulx generates automatically a default individual parameter element called “IndivParameters” with all values set to 1. This element can be modified (button EDIT). New elements can be created with the button “+”. Two different types of individual parameter elements are available:

• Manual: One value per parameter to type in. The required parameters are automatically listed.

• External: An external text file with either:
• A single row and one column per parameter. The headers must correspond to the parameter names.
• Several rows, a first column with header “id”, occasion columns (optional) and one column per parameter. The headers must correspond to the parameter names, and to the occasion names if applicable.

The external file can be tab, comma or semicolon separated. Available file extension are: .csv or .txt.

#### Individual parameters elements imported from Monolix

Upon import of a Monolix run, several individual parameters elements are created automatically:

• mlx_IndivInit: [when POP.PARAM task has not run]a vector of individual parameters corresponding to the initial values of the population parameters in Monolix, i.e with covariate betas and random effects set to zero. For instance, $$V=V_{pop,ini}$$
• mlx_PopIndiv[when POP.PARAM task has run]a vector of individual parameters corresponding to the population parameters estimated by Monolix, i.e with covariate betas and random effects set to zero. For instance, $$V=V_{pop,est}$$
• mlx_PopIndivCov[when POP.PARAM task has run and covariates are defined in the Monolix data set]a table of individual parameters corresponding to the population parameters and the impact of the covariates, but random effects set to zero. For instance, $$V=V_{pop} \times \left( \frac{WT}{70} \right) ^{\beta_{V,WT}}$$
• mlx_EBEs[when EBEs task has run] a table of individual parameters corresponding to the EBEs (conditional mode) estimated by Monolix (as displayed in Monolix Results > Indiv. param > Cond. mode.)
• mlx_CondMean[when COND. DISTRIB. task has run] a table of individual parameters corresponding to the conditional mean estimated by Monolix (as displayed in in Monolix Results > Indiv. param > Cond. mean.)
• mlx_CondDistSample[when COND. DISTRIB. task has run] a table of individual parameters corresponding to one sample of the conditional distribution (first replicate of the Monolix result file IndividualParameters/simulatedIndividualParameters.txt).