prior {EMC2} | R Documentation |
Prior specification
Description
Specify priors for the chosen model. These values are entered manually by default but can be
recycled from another prior (given in the update
argument).
Usage
prior(
design,
type = "standard",
update = NULL,
do_ask = NULL,
fill_default = TRUE,
...
)
Arguments
design |
Design list for which a prior is constructed, typically the output of |
type |
Character. What type of group-level model you plan on using i.e. |
update |
Prior list from which to copy values |
do_ask |
Character. For which parameter types or hyperparameters to ask for prior specification,
i.e. |
fill_default |
Boolean, If |
... |
Either values to prefill, i.e. |
Details
Where a value is not supplied, the user is prompted to enter numeric values (or functions that evaluate to numbers).
To get the prior help use prior_help(type)
. With type
e.g. 'diagonal'.
Value
A prior list object
Examples
# First define a design for the model
design_DDMaE <- design(data = forstmann,model=DDM,
formula =list(v~0+S,a~E, t0~1, s~1, Z~1, sv~1, SZ~1),
constants=c(s=log(1)))
# Then set up a prior using prior
p_vector=c(v_Sleft=-2,v_Sright=2,a=log(1),a_Eneutral=log(1.5),a_Eaccuracy=log(2),
t0=log(.2),Z=qnorm(.5),sv=log(.5),SZ=qnorm(.5))
psd <- c(v_Sleft=1,v_Sright=1,a=.3,a_Eneutral=.3,a_Eaccuracy=.3,
t0=.4,Z=1,sv=.4,SZ=1)
# Here we left the variance prior at default
prior_DDMaE <- prior(design_DDMaE,mu_mean=p_vector,mu_sd=psd)
# Also add a group-level variance prior:
pscale <- c(v_Sleft=.6,v_Sright=.6,a=.3,a_Eneutral=.3,a_Eaccuracy=.3,
t0=.2,Z=.5,sv=.4,SZ=.3)
df <- .4
prior_DDMaE <- prior(design_DDMaE,mu_mean=p_vector,mu_sd=psd, A = pscale, df = df)
# If we specify a new design
design_DDMat0E <- design(data = forstmann,model=DDM,
formula =list(v~0+S,a~E, t0~E, s~1, Z~1, sv~1, SZ~1),
constants=c(s=log(1)))
# We can easily update the prior
prior_DDMat0E <- prior(design_DDMat0E, update = prior_DDMaE)