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.s
N
alpha.rot
alpha.orth
agreement
alpha.rot
and alpha.orth
. This measures agreement between
the two alpha
s.
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")