cordexch (Statistics Toolbox)

D-optimal design of experiments - coordinate exchange algorithm.

Syntax

settings = cordexch(nfactors,nruns)
[settings,X] = cordexch(nfactors,nruns)
[settings,X] = cordexch(nfactors,nruns,'model')

Description

settings = cordexch(nfactors,nruns) generates the factor settings matrix, settings, for a D-optimal design using a linear additive model with a constant term. settings has nruns rows and nfactors columns.

[settings,X] = cordexch(nfactors,nruns) also generates the associated design matrix, X.

[settings,X] = cordexch(nfactors,nruns,'model') produces a design for fitting a specified regression model. The input, 'model', can be one of these strings:

'interaction' - includes constant, linear, and cross product terms.
'quadratic' - interactions plus squared terms.
'purequadratic' - includes constant, linear and squared terms.

Example

The D-optimal design for two factors in nine run using a quadratic model is the 3² factorial as shown below:

settings = cordexch(2,9,'quadratic')

settings =

    -1     1
     1     1
     0     1
     1    -1
    -1    -1
     0    -1
     1     0
     0     0
    -1     0