Control Options for SAEM

Usage

saemControl(
  seed = 99,
  nBurn = 200,
  nEm = 300,
  nmc = 3,
  nu = c(2, 2, 2),
  print = 1,
  trace = 0,
  covMethod = c("linFim", "fim", "r,s", "r", "s", ""),
  calcTables = TRUE,
  logLik = FALSE,
  nnodesGq = 3,
  nsdGq = 1.6,
  optExpression = TRUE,
  literalFix = TRUE,
  adjObf = TRUE,
  sumProd = FALSE,
  addProp = c("combined2", "combined1"),
  tol = 1e-06,
  itmax = 30,
  type = c("nelder-mead", "newuoa"),
  powRange = 10,
  lambdaRange = 3,
  odeRecalcFactor = 10^(0.5),
  maxOdeRecalc = 5L,
  perSa = 0.75,
  perNoCor = 0.75,
  perFixOmega = 0.1,
  perFixResid = 0.1,
  compress = TRUE,
  rxControl = NULL,
  sigdig = NULL,
  sigdigTable = NULL,
  ci = 0.95,
  muRefCov = TRUE,
  muRefCovAlg = TRUE,
  handleUninformativeEtas = TRUE,
  ...
)

Arguments

seed

Random Seed for SAEM step. (Needs to be set for reproducibility.) By default this is 99.

nBurn

Number of iterations in the first phase, ie the MCMC/Stochastic Approximation steps. This is equivalent to Monolix's K_0 or K_b.

nEm

Number of iterations in the Expectation-Maximization (EM) Step. This is equivalent to Monolix's K_1.

nmc

Number of Markov Chains. By default this is 3. When you increase the number of chains the numerical integration by MC method will be more accurate at the cost of more computation. In Monolix this is equivalent to L.

nu

This is a vector of 3 integers. They represent the numbers of transitions of the three different kernels used in the Hasting-Metropolis algorithm. The default value is c(2,2,2), representing 40 for each transition initially (each value is multiplied by 20).

The first value represents the initial number of multi-variate Gibbs samples are taken from a normal distribution.

The second value represents the number of uni-variate, or multi- dimensional random walk Gibbs samples are taken.

The third value represents the number of bootstrap/reshuffling or uni-dimensional random samples are taken.

print

The number it iterations that are completed before anything is printed to the console. By default, this is 1.

trace

An integer indicating if you want to trace(1) the SAEM algorithm process. Useful for debugging, but not for typical fitting.

covMethod

Method for calculating covariance. In this discussion, R is the Hessian matrix of the objective function. The S matrix is the sum of each individual's gradient cross-product (evaluated at the individual empirical Bayes estimates).

"linFim" Use the Linearized Fisher Information Matrix to calculate the covariance.

"fim" Use the SAEM-calculated Fisher Information Matrix to calculate the covariance.

"r,s" Uses the sandwich matrix to calculate the covariance, that is: $R^-1 \times S \times R^-1$

"r" Uses the Hessian matrix to calculate the covariance as $2\times R^-1$

"s" Uses the crossproduct matrix to calculate the covariance as $4\times S^-1$

"" Does not calculate the covariance step.

calcTables

This boolean is to determine if the foceiFit will calculate tables. By default this is TRUE

logLik

boolean indicating that log-likelihood should be calculate by Gaussian quadrature.

nnodesGq

number of nodes to use for the Gaussian quadrature when computing the likelihood with this method (defaults to 1, equivalent to the Laplacian likelihood)

nsdGq

span (in SD) over which to integrate when computing the likelihood by Gaussian quadrature. Defaults to 3 (eg 3 times the SD)

optExpression

Optimize the rxode2 expression to speed up calculation. By default this is turned on.

literalFix

boolean, substitute fixed population values as literals and re-adjust ui and parameter estimates after optimization; Default is `TRUE`.

adjObf

is a boolean to indicate if the objective function should be adjusted to be closer to NONMEM's default objective function. By default this is TRUE

sumProd

Is a boolean indicating if the model should change multiplication to high precision multiplication and sums to high precision sums using the PreciseSums package. By default this is FALSE.

addProp

specifies the type of additive plus proportional errors, the one where standard deviations add (combined1) or the type where the variances add (combined2).

The combined1 error type can be described by the following equation:

$$y = f + (a + b\times f^c) \times \varepsilon$$

The combined2 error model can be described by the following equation:

$$y = f + \sqrt{a^2 + b^2\times f^{2\times c}} \times \varepsilon$$

Where:

- y represents the observed value

- f represents the predicted value

- a is the additive standard deviation

- b is the proportional/power standard deviation

- c is the power exponent (in the proportional case c=1)

tol

This is the tolerance for the regression models used for complex residual errors (ie add+prop etc)

itmax

This is the maximum number of iterations for the regression models used for complex residual errors. The number of iterations is itmax*number of parameters

type

indicates the type of optimization for the residuals; Can be one of c("nelder-mead", "newuoa")

powRange

This indicates the range that powers can take for residual errors; By default this is 10 indicating the range is c(-10, 10)

lambdaRange

This indicates the range that Box-Cox and Yeo-Johnson parameters are constrained to be; The default is 3 indicating the range c(-3,3)

odeRecalcFactor

The ODE recalculation factor when ODE solving goes bad, this is the factor the rtol/atol is reduced

maxOdeRecalc

Maximum number of times to reduce the ODE tolerances and try to resolve the system if there was a bad ODE solve.

perSa

This is the percent of the time the `nBurn` iterations in phase runs runs a simulated annealing.

perNoCor

This is the percentage of the MCMC phase of the SAEM algorithm where the variance/covariance matrix has no correlations. By default this is 0.75 or 75 Monte-carlo iteration.

perFixOmega

This is the percentage of the `nBurn` phase where the omega values are unfixed to allow better exploration of the likelihood surface. After this time, the omegas are fixed during optimization.

perFixResid

This is the percentage of the `nBurn` phase where the residual components are unfixed to allow better exploration of the likelihood surface.

compress

Should the object have compressed items

rxControl

`rxode2` ODE solving options during fitting, created with `rxControl()`

sigdig

Specifies the "significant digits" that the ode solving requests. When specified this controls the relative and absolute tolerances of the ODE solvers. By default the tolerance is 0.5*10^(-sigdig-2) for regular ODEs. For the sensitivity equations the default is 0.5*10\^(-sigdig-1.5) (sensitivity changes only applicable for liblsoda). This also controls the atol/rtol of the steady state solutions. The ssAtol/ssRtol is 0.5*10\^(-sigdig) and for the sensitivities 0.5*10\^(-sigdig+0.625). By default this is unspecified (NULL) and uses the standard atol/rtol.

sigdigTable

Significant digits in the final output table. If not specified, then it matches the significant digits in the `sigdig` optimization algorithm. If `sigdig` is NULL, use 3.

ci

Confidence level for some tables. By default this is 0.95 or 95% confidence.

muRefCov

This controls if mu-referenced covariates in `saem` are handled differently than non mu-referenced covariates. When `TRUE`, mu-referenced covariates have special handling. When `FALSE` mu-referenced covariates are treated the same as any other input parameter.

muRefCovAlg

This controls if algebraic expressions that can be mu-referenced are treated as mu-referenced covariates by:

1. Creating a internal data-variable `nlmixrMuDerCov#` for each algebraic mu-referenced expression

2. Change the algebraic expression to `nlmixrMuDerCov# * mu_cov_theta`

3. Use the internal mu-referenced covariate for saem

4. After optimization is completed, replace `model()` with old `model()` expression

5. Remove `nlmixrMuDerCov#` from nlmix2 output

In general, these covariates should be more accurate since it changes the system to a linear compartment model. Therefore, by default this is `TRUE`.

handleUninformativeEtas

boolean that tells nlmixr2's saem to calculate uninformative etas and handle them specially (default is `TRUE`).

...

Additional arguments passed to nlmixr2est::saemControl().

Value

List of options to be used in nlmixr2 fit for SAEM.

Author

Wenping Wang & Matthew L. Fidler

Control Options for SAEM

Usage

Arguments

Value

See also

Author