TransitionMatrix: Multi-state Transition Functions

In RMark: R Code for Mark Analysis

Multi-state Transition Functions

Description

TransitionMatrix: Creates a transition matrix of movement parameters for a multi-state(strata) model. It computes all Psi values for a multi-strata mark model and constructs a transition matrix. Standard errors and confidence intervals can also be obtained.

Usage

TransitionMatrix(x,vcv.real=NULL)

        find.possible.transitions(ch)

        transition.pairs(ch)

Arguments

x	Estimate table from get.real with a single record for each possible transition
vcv.real	optional variance-covariance matrix from the call to get.real
ch	vector of capture history strings for a multi-state analysis

Details

find.possible.transitions: Finds possible transitions; essentially it identifies where stratum label A and B are in the same ch for all labels but the the transition could be from A to B or B to A or even ACB which is really an A to C and C to B transition.

transition.pairs: Computes counts of transition pairs. The rows are the "from stratum" and the columns are the "to stratum". So AB would be in the first row second column and BA would be in the second row first column. All intervening 0s are ignored. These are transition pairs so AB0C is A to B and B to C but not A to C.

Value

TransitionMatrix: returns either a transition matrix (vcv.real=NULL) or a list of matrices (vcv.real specified) named TransitionMat (transition matrix), se.TransitionMat (se of each transition), lcl.TransitionMat (lower confidence interval limit for each transition), and ucl.TransitionMat (upper confidence interval limit for each transition). find.possible.transitions returns a 0/1 table where 1 means that t both values are in one or more ch strings and transition.pairs returns a table of counts of transition pairs.

Author(s)

Jeff Laake

See Also

get.real

Examples

# This example is excluded from testing to reduce package check time
data(mstrata)
# Show possible transitions in first 15 ch values
find.possible.transitions(mstrata$ch[1:15])
# Show transtion pairs for same data
transition.pairs(mstrata$ch[1:15])
#limit transtions to 2 and 3 character values for first 30 ch
transition.pairs(substr(mstrata$ch[1:30],2,3))

# fit the sequence of multistrata models as shown for ?mstrata
run.mstrata=function()
{
#
# Process data
#
mstrata.processed=process.data(mstrata,model="Multistrata")
#
# Create default design data
#
mstrata.ddl=make.design.data(mstrata.processed)
#
#  Define range of models for S; note that the betas will differ from the output
#  in MARK for the ~stratum = S(s) because the design matrix is defined using
#  treatment contrasts for factors so the intercept is stratum A and the other
#  two estimates represent the amount that survival for B abd C differ from A.
#  You can use force the approach used in MARK with the formula ~-1+stratum which
#  creates 3 separate Betas - one for A,B and C.
#
S.stratum=list(formula=~stratum)
S.stratumxtime=list(formula=~stratum*time)
#
#  Define range of models for p
#
p.stratum=list(formula=~stratum)
#
#  Define range of models for Psi; what is denoted as s for Psi
#  in the Mark example for Psi is accomplished by -1+stratum:tostratum which
#  nests tostratum within stratum.  Likewise, to get s*t as noted in MARK you
#  want ~-1+stratum:tostratum:time with time nested in tostratum nested in
#  stratum.
#
Psi.s=list(formula=~-1+stratum:tostratum)
#
# Create model list and run assortment of models
#
model.list=create.model.list("Multistrata")
#
# Add on a specific model that is paired with fixed p's to remove confounding
#
p.stratumxtime=list(formula=~stratum*time)
p.stratumxtime.fixed=list(formula=~stratum*time,fixed=list(time=4,value=1))
model.list=rbind(model.list,c(S="S.stratumxtime",p="p.stratumxtime.fixed",
               Psi="Psi.s"))
#
# Run the list of models
#
mstrata.results=mark.wrapper(model.list,data=mstrata.processed,ddl=mstrata.ddl,delete=TRUE)
#
# Return model table and list of models
#
return(mstrata.results)
}
mstrata.results=run.mstrata()
mstrata.results
# for the best model, get.real to get a list containing all Psi estimates
#  and the v-c matrix
Psilist=get.real(mstrata.results[[1]],"Psi",vcv=TRUE)
Psivalues=Psilist$estimates
# call Transition matrix using values from time==1; the call to the function
# must only contain one record for each possible transition. An error message is
# given if not the case
TransitionMatrix(Psivalues[Psivalues$time==1,])
# call it again but specify the vc matrix to get se and conf interval
TransitionMatrix(Psivalues[Psivalues$time==1,],vcv.real=Psilist$vcv.real)

RMark documentation built on Aug. 14, 2022, 1:05 a.m.