| ccd.pick {rsm} | R Documentation |
This function looks at all combinations of specified design parameters
for central-composite designs, calculates other quantities such as
the 'alpha' values for rotatability and orthogonal blocking, imposes
specified restrictions, and outputs the best combinations in a order.
This serves as an aid in identifying good designs. The design itself can
then be generated using ccd.
ccd.pick(k, n.c = 2^k, n0.c = 1:10, blks.c = 1, n0.s = 1:10, bbr.c = 1,
wbr.s = 1, bbr.s = 1, best = 10, sortby = c("agreement", "N"),
restrict)
k |
Number of factors in the design |
n.c |
Number(s) of factorial points in each cube block |
n0.c |
Numbers(s) of center points in each cube block |
blks.c |
Number(s) of cube blocks that together comprise one rep of the cube portion |
n0.s |
Numbers(s) of center points in each star (axis-point) block |
bbr.c |
Number(s) of copies of each cube block |
wbr.s |
Number(s) of replications of each star poit within a block |
bbr.s |
Number(s) of copies of each star block |
best |
How many designs to list. Use best=NULL to list them all |
sortby |
String(s) containing numeric expressions that are each evaluated and used as sorting key(s).
Specify sortby=NULL if no sorting is desired. |
restrict |
Optional string(s) containing Boolean expressions that are each evaluated. Only combinations where all
expressions are TRUE are retained. |
A grid is created with all combinations of n.c, n0.c, ..., bbr.s.
Then for each row of the grid, several additional variables
are computed:
n.sNalpha.rotalpha.orthagreementalpha.rot and alpha.orth. This measures agreement between
the two alphas.
If restrict is provided, each expression is evaluated
and only the rows where the expression is TRUE are kept.
(Regardless of restrict, rows are eliminated where there are
insufficient degrees of freedom to estimate all needed effects for a
second-order model.)
The rows are
sorted according to the expressions in sortby; the default is to sort
by agreement and N, which is suitable for finding designs
that are both rotatable and orthogonally blocked.
A data.frame containing best or fewer rows, and variables
n.c, n0.c, blks.c, n.s, n0.s, bbr.c,
wbr.s, bbr.s, N, alpha.rot, and alpha.orth,
as described above.
Russell V. Lenth
Meyers, RH and Montgomery, DC (2002), Response Surface Methodology (2nd ed.), Wiley-Interscience.
library(rsm) ### List CCDs in 3 factors with between 10 and 14 runs per block ccd.pick(3, n0.c=2:6, n0.s=2:8) ### Generate the design that is listed first. ccd(3, n0=c(6,4)) ### Find designs in 5 factors containing 1, 2, or 4 cube blocks ### of 8 or 16 runs, 1 or 2 reps of each axis point, ### and no more than 70 runs altogether ccd.pick(5, n.c=c(8,16), blks.c=c(1,2,4), wbr.s=1:2, restrict="N<=70")