add.design.data: Add design data

Description Usage Arguments Details Value Note Author(s) See Also Examples

View source: R/add.design.data.R

Description

Creates new design data fields in (ddl) that bin the fields cohort, age or time. Other fields (e.g., effort value for time) can be added to ddl with R commands.

Usage

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add.design.data(data, ddl, parameter, type = "age", bins = NULL,
  name = NULL, replace = FALSE, right = TRUE)

Arguments

data

processed data list resulting from process.data

ddl

current design dataframe initially created with make.design.data

parameter

name of model parameter (e.g., "Phi" for CJS models)

type

either "age", "time" or "cohort"

bins

bins for grouping

name

name assigned to variable in design data

replace

if TRUE, replace any variable with same name as name

right

If TRUE, bin intervals are closed on the right

Details

Design data can be added to the parameter specific design dataframes with R commands. Often the additional fields will be functions of cohort, age or time. add.design.data provides an easy way to add fields that bin (put into intervals) the original values of cohort, age or time. For example, age may have levels from 0 to 10 which means the formula ~age will have 11 parameters, one for each level of the factor. It might be more desirable and more parimonious to have a simpler 2 age class model of young and adults. This can be done easily by adding a new design data field that bins age into 2 intervals (age 0 and 1+) as in the following example:

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 ddl=make.design.data(proc.example.data)
ddl=add.design.data(proc.example.data,ddl,parameter="Phi",type="age",
bins=c(0,.5,10),name="2ages") 

By default, the bins are open on the left and closed on the right (i.e., binning x by (x1,x2] is equivalent to x1<x<=x2) except for the first interval which is closed on the left. Thus, for the above example, the age bins are [0,.5] and (.5,10]. Since the ages in the example are 0,1,2... using any value >0 and <1 in place of 0.5 would bin the ages into 2 classes of 0 and 1+. This behavior can be modified by changing the argument right=FALSE to create an interval that is closed on the left and open on the right. In some cases this can make reading the values of the levels somewhat easier. It is important to recognize that the new variable is only added to the design data for the defined parameter and can only be used in model formula for that parameter. Multiple calls to add.design.data can be used to add the same or different fields for the various parameters in the model. For example, the same 2 age class variable can be added to the design data for p with the command:

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ddl=add.design.data(proc.example.data,ddl,parameter="p",type="age",
bins=c(0,.5,10),name="2ages") 

The name must be unique within the parameter design data, so they should not use pre-defined values of group, age, Age, time, Time, cohort, Cohort. If you choose a name that already exists in the design data for the parameter, it will not be added but it can replace the variable if replace=TRUE. For example, the 2ages variable can be re-defined to use 0-1 and 2+ with the command:

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ddl=add.design.data(proc.example.data,ddl,parameter="Phi",type="age",
bins=c(0,1,10),name="2ages",replace=TRUE) 

Keep in mind that design data are stored with the mark model object so if a variable is redefined, as above, this could become confusing if some models have already been constructed using a different definition for the variable. The model formula and names would appear to be identical but they would have a different model structure. The difference would be apparent if you examined the design data and design matrix of the model object but would the difference would be transparent based on the model names and formula. Thus, it would be best to avoid constructing models from design data fields with different structures but the same name.

Value

Design data list with new field added for the specified parameter. See make.design.data for a description of the list structure.

Note

For the specific case of "closed" capture models, the parameters p (capture probability) and c (recapture probability) can be treated in a special fashion. Because they really the same type of parameter, it is useful to be able to share a common model structure (i.e., same columns in the design matrix). This is indicated with the share=TRUE element in the model description for p. If the parameters are shared then the additional covariate c is added to the design data, which is c=0 for parameter p and c=1 for parameter c. This enables an additive model to be developed where recapture probabilities mimic the pattern in capture probabilities except for an additive constant. The covariate c can only be used in the model for p if share=TRUE. If the latter is not set using c in a formula will result in an error. Likewise, if share=TRUE, then the design data for p and c must be the same because the design data are merged in constructing the design matrix. Thus if you add design data for parameter p, you should add a similar field for parameter c if you intend to fit shared models for the two parameters. If the design data do not match and you try to fit a shared model, an error will result.

Author(s)

Jeff Laake

See Also

make.design.data, process.data

Examples

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# This example is excluded from testing to reduce package check time
data(example.data)
example.data.proc=process.data(example.data)
ddl=make.design.data(example.data.proc)
ddl=add.design.data(example.data.proc,ddl,parameter="Phi",type="age",
  bins=c(0,.5,10),name="2ages")
ddl=add.design.data(example.data.proc,ddl,parameter="p",type="age",
bins=c(0,.5,10),name="2ages")
ddl=add.design.data(example.data.proc,ddl,parameter="Phi",type="age",
bins=c(0,1,10),name="2ages",replace=TRUE)

RMark documentation built on Nov. 7, 2019, 1:06 a.m.

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