Function to create user-specified interactions for a Siena model.
This function allows the user to include or exclude an interaction effect in a Siena effects object.
includeInteraction(myeff, ..., include = TRUE, name = myeff$name[1],
type = "eval", interaction1 = rep("", 3), interaction2 = rep("", 3),
fix = FALSE, test = FALSE, parameter = NULL, random = FALSE,
character = FALSE, verbose = TRUE)myeff |
a Siena effects object as created by |
... |
2 or 3 short names to identify the effects which should be interacted. |
include |
Boolean. default TRUE, but can be switched to FALSE to turn off an interaction. |
name |
Name of dependent variable (network or behavior) for which interactions are being defined. Defaults to the first in the effects object. |
type |
Type of effects to be interacted. |
interaction1 |
Vector of Siena objects where needed to completely identify the effect e.g. covariate name or behavior variable name. Trailing blanks may be omitted. |
interaction2 |
Vector of siena objects where needed to completely identify the effect e.g. covariate name or behavior variable name. Trailing blanks may be omitted. |
fix |
Boolean. Are the effects to be fixed at the value stored in
|
test |
Boolean. Are the effects to be tested or not (requires |
parameter |
Value of internal effect parameter of this interaction effect. If NULL, no change is made. |
random |
For specifying that the interaction effect will vary randomly;
not relevant for |
character |
Boolean: are the effect names character strings or not. |
verbose |
Boolean: should the print of altered effects be produced. |
The details provided should uniquely identify up to three
effects. If so, an interaction effect will be created and included or
not in the model.
Whether interactions between two or three given effects
can be created depends on their interactionType (which can be, for
dependent network variables, empty, ego, or dyadic; and for dependent
behavioral variables, empty or OK). Consult the section on Interaction
Effects in the manual for this. The interactionType is shown
in the list of effects obtained from the function
effectsDocumentation.
The short names must not be set between quotes,
unless you use character=TRUE.
From the point of view of model building it is usually advisable, when
including an interaction effect in a model, also to include the
corresponding main effects. This is however not enforced
by includeInteraction().
Interaction effects are constructed from effects with shortName
unspInt (for networks) and behUnspInt (for behavior)
by specifying their elements effect1 and effect2,
and possibly effect3.
The number of possible user-specified interaction effects is limited
by the parameters nintn (for dependent network variables)
and behNintn (for dependent behavior variables)
in the call of getEffects, which determine the numbers of
effects with shortNames unspInt and behUnspInt.
The input names interaction1 and interaction2 do not themselves
refer to created interactions, but to dependence of the base effects on
other variables in the data set.
They are used to completely identify the effects.
To set attributes of interaction effects in the effects object,
function setEffect can also be used with short name
unspInt or behUnspInt, and further using parameters
effect1 and effect2, and possibly effect3.
Further information about Siena effects objects is given
in the help page for getEffects.
A list of all effects in a given effects object (e.g., myeff),
including their names of dependent variables, effect names, short names,
and values of interaction1 and interaction2 (if any),
is obtained by executing effectsDocumentation(myeff).
An updated version of the input effects object; if include,
containing the interaction effect between "effect1" and "effect2" and
possibly "effect3"; if not, without this interaction effect.
The shortName of the interaction effect is "unspInt" for network effects
and "behUnspInt" for behavior effects.
If verbose=TRUE, details of the fields altered will be printed.
Ruth Ripley, Tom Snijders
mynet <- sienaDependent(array(c(s501, s502, s503), dim=c(50, 50, 3)))
alc <- varCovar(s50a)
mydata <- sienaDataCreate(mynet, alc)
myeff <- getEffects(mydata)
myeff <- includeEffects(myeff, transTrip)
myeff <- includeInteraction(myeff, recip, outAct)
myeff <- includeEffects(myeff, egoX, altX, simX, interaction1="alc")
myeff <- includeInteraction(myeff, recip, simX, interaction1=c("", "alc"))
myeff
# How to set the effect parameter of an interaction:
myeff <- getEffects(mydata)
myeff <- setEffect(myeff, gwespFF, parameter=69)
myeff <- includeInteraction(myeff, recip, gwespFF, parameter=69)
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