startLimits function

startLimits - Distance function starting values and limits

Returns starting values and limits (boundaries) for the parameters of distance functions. This function is called by other routines in Rdistance, and is not intended to be called by the user. Replace this function in the global environment to change boundaries and starting values.

startLimits(ml)

Arguments

• ml: Either a Rdistance 'model frame' or an Rdistance 'fitted object'. Both are of class "dfunc". Rdistance 'model frames' are lists containing components necessary to estimate a distance function, but no estimates. Rdistance 'model frames' are typically produced by calls to parseModel. Rdistance 'fitted objects' are typically produced by calls to dfuncEstim. 'Fitted objects' are 'model frames' with additional components such as the parameters estimates, log likelihood value, convergence information, and the variance- covariance matrix of the parameters.

Returns

A list containing the following components - start: Vector of starting values for parameters of the likelihood and expansion terms.

• lowlimit: Vector of lower limits for the likelihood parameters and expansion terms.

• uplimit: Vector of upper limits for the likelihood parameters and expansion terms.

• names: Vector of names for the likelihood parameters and expansion terms.

The length of each vector in the return is: (Num expansions) + 1 + 1*(like %in% c("hazrate")) + (Num Covars).

Examples

data(sparrowDf)
  
  # Half-normal start limits
  modList <- parseModel(
       data = sparrowDf
     , formula = dist ~ 1
     , likelihood = "halfnorm"
  )
  startLimits(modList)
  
  # Half-normal with expansions
  modList <- parseModel(
       data = sparrowDf
     , formula = dist ~ 1
     , likelihood = "halfnorm"
     , expansions = 3
  )
  startLimits(modList)
  
  # Hazard rate start limits
  modList$likelihood <- "hazrate"
  startLimits(modList)
  
  # Neg exp start limits
  modList$likelihood <- "negexp"
  startLimits(modList)

See Also

dfuncEstim