Control records

A NONMEM control record begins with a record reserved word that starts with "$". Unless specified, each control record section in this chapter begins with a code block for the control record's usage and an example.

Overview of a NONMEM run

Each NONMEM problem's run consists of a sequence of steps.

  1. NONMEM loads information from a Model Specification File, if $MSFI is present NONMEM makes a single call to PRED (with ICALL=0), at the beginning of the run, to allow PRED to undertake run initialization (INITL).
  2. NONMEM makes a single call to PRED (with ICALL=1), at the beginning of every problem, to allow PRED to undertake problem initialization (INITL).
  3. SIMULATION STEP: NONMEM inputs initial fixed effects parameters from file specified by $CHAIN, if record is present NONMEM performs simulation (with ICALL=4) (if $SIMULATION present).
  4. INITIAL ESTIMATE STEP (with ICALL=2): NONMEM obtains initial estimates for theta, omega, sigma (if the control stream does not provide all initial estimates).
  5. ESTIMATION STEP (with ICALL=2): NONMEM inputs initial ETAs from file specified by $ETAS and $PHIS, if record is present NONMEM searches for parameter values that mini- mize the objective function (if $ESTIMATION present). With NONMEM 7, multiple Estimation Steps can be implemented in a single problem. A sequence of two or more Estimation Steps will result in the sequential execution of each.
  6. COVARIANCE STEP (with ICALL=2) NONMEM obtains a variance-covariance matrix of the estimator and related information such as standard errors (if $COVARIANCE present).

  7. FINALIZATION STEP (with ICALL=2,5,6) NONMEM obtains the following as needed:

    • Classification into subpopulations (if a MIXTURE model is used)(FNLMOD).
    • Posthoc estimates of ETA.
    • Nonparametric step (NONPAR, with ICALL=2): NONMEM obtains either marginal cumulatives or conditional (nonparametric)
    • Estimates of ETAs for $NONPARAMETRIC.
    • PRED-defined values from NMPRD4 (NP4F) (for tables and scatterplots).
  8. NONMEM computes WRES and other diagnostics if they are to be displayed in tables or scatters. (PRRES)
  9. NONMEM makes a single call to PRED (with ICALL=3), at the end of every problem (and subproblem), to allow PRED to undertake problem finalization.
  10. TABLE STEP: NONMEM constructs tables (if $TABLE present). Same for $SCATTERPLOT.
Calendar 2026 Sep 17
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