vector of the number of levels for the factors in the design.
OPTIONAL ARGUMENTS:
factor.names
object that names the factors.
This may be a vector of character strings which are the names of the factors.
It may also be a list, in which case the names attribute of the list
is the names of the factors,
and the components of the list (which need not be of mode character) label
the levels of the corresponding factor.
If factor names are not given, they default to
A,
B, etc.
If levels are not given, they default to
the factor name (possibly abbreviated) followed by level numbers.
replications
the number of times the complete design should be replicated.
row.names
names to use for the rows of the design.
The default is 1:nrows, where
nrows is the number of observations in the
design.
fraction
definition for the fraction desired in a fractional factorial
design.
This may either be a numerical fraction
(e.g, 1/4 for a quarter replicate),
or a model formula giving one or more defining contrasts
(e.g., A:B:D + B:C:E").
Fractional factorials are provided only for 2-level factors.
By default, a full factorial design is created.
VALUE:
a design corresponding to the factors specified.
The
design object is a data frame,
with variables in the frame corresponding to each of the factors
requested in the design.
In the case that
fraction is specified,
an attribute,
defcon,
will supply the defining contrast(s),
and if
which.half is supplied,
this will also be retained as an attribute.
DETAILS:
fac.design chooses defining contrasts
for fractional designs
from a standard list called
dimdc.list.
WARNING:
Avoid using factor names
F
and
T as these can get confused with
FALSE
and
TRUE.
The default factor names skips these two letters.
SEE ALSO:
,
,
,
,
,
,
.
EXAMPLES:
fnames <- list(react = c("4mod", "5mol"),
acidcon=c("con", "dil"),
acidamt=c("2mol", "2.5mol"),
reactim=c("2", "4"),
reactem=c("low", "high"))
# A 1/4 replicate of a 2^5 design, specifying the -1
# fraction for the first contrast
davies.design <- fac.design(rep(2, 5), factor.names=fnames,
fraction= ~ - react:acidamt:reactim + react:acidcon:reactem)