*Macros for the Design and Analysis of Experiments* |

## ADXCCD: Construct Central Composite Designs

**%adxccd**(*ds, nf, nr, nc, alpha, nb*)

where

*ds* | is the name of the output SAS data set for the constructed
design. This data set contains variables for design factors
and for a block factor, if the design uses blocking.
Default names are used. The default names for design factors
are T1, T2, T3, and so on; the default name for a block
factor is BLOCK. |

*nf* | is the number of design factors. |

*nr* | is the number of points in the factorial portion of the
design and must be a power of 2. There must be a resolution
5 design in *nf* factors for the value of *nr* you
specify. For example, if *nf*=5, then *nr* can
be 16, but not 8. |

*nc* | is the number of centerpoints in the design. If you do
not use blocking, *nc* is a nonnegative integer. If
you use blocking, *nc* is two integers separated by a
slash. The first integer gives the number of centerpoints
in each block in the factorial portion of the design, and
the second integer gives the number of centerpoints for
the axial block. |

*alpha* | is the value of the axial extreme. |

*nb* | is the number of blocks in the design. Since the blocks
for a design are the blocks for the factorial portion
together with the axial block, the number of blocks must be
of the form 2^{n}+1 for some *n*. If the design does not use
blocking, *nb* can be omitted. |

The ADXCCD macro constructs a central composite design according
to the parameters you specify and outputs the design to a SAS
data set.

Suppose you want to examine a response surface over 5 factors.
You can use the ADXPCC macro to find that there
is a design in 33 runs and 2 blocks. One block is a half-fraction
of the full 2^{5} design, and the other block is the axial
portion of the design. You can produce the output from the ADXPCC
macro and construct the design with the following statements:

%adxgen
%adxff
%adxcc
%adxinit
%adxpcc(5)
%adxccd(a,5,16,6/1,2.0000,2)

The design is output to data set A. Note that 6/1 is used for
*nc*. Since the design involves blocking, this specifies
that the factorial block contains 6 centerpoints and the axial
block contains 1 centerpoint.
You can produce a design (output to data set B) with just one
centerpoint in the axial block with the following statements:

%adxgen
%adxff
%adxcc
%adxinit
%adxccd(b,5,16,0/1,2.0000,2)

Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.