DD_weight_1 function

The first derivative of the Ds-optimality criterion with respect to the model parameters

The first derivative of the Ds-optimality criterion with respect to the model parameters. This is a sub-function of D_weight to run one iteration of Newton-Raphson method.

DD_weight_1(W, T, X, inv, inv1, order)

Arguments

• W: A numeric vector. The first K-1 weights for a given design
• T: A numeric vector. Model parameter values for the 5PL model
• X: A numeric vector. K dose levels for a given design
• inv: A numeric matrix. Inverse information matrix for the 5PL model
• inv1: A numeric matrix. Inverse information matrix for the 4PL model
• order: numeric. The number of model paraemters