GLM: Generalized Linear Modelling on variable costs of individual...

In SECFISH: Disaggregate Variable Costs

Description

Function to explore GLMs on the individual vessel data to test the significance of metier and transversal variables on the variable costs structure.

The function should be run on COSTS.csv file produced by EA function run previously on individual vessel data. This file should be correctly stored in the working directory. Only the fleet segments with a minimum number of observations are considered. This value can be set by the user as input in the GLM function, defining thr_obs value. It is also possible to define the most significant metier to be used in the GLM through the percentage of cumulative estimated on the number of vessels observed by metier. A buffer of 5 percent on the cumulative percentage is applied by default.

Usage

GLM(COSTS,thr_obs,thr_cum,FORMULA_LAB1,FORMULA_LAB2,path)

Arguments

COSTS	Data frame built applying EA function on individual vessel data and automatically saved as COSTS.csv in the working directory.
thr_obs	threshold to be used for carry out the modelling to a fleet segment.
thr_cum	threshold to be used for selecting the metier to be used in the modelling according to a cumulative metier-number of vessels observed.
FORMULA_LAB1	Option for labour costs modelling (additive model).
FORMULA_LAB2	Option for labour costs modelling (multiplicative model).
path	Path where the results have to be saved.

Value

COSTS	data.frame: see format in the package (type CO in the console).
thr_obs	minimum number of observations needed to run fit the GLM; e.g. 30 means that only the fleet segments with at least 30 vessels observed will be modelled.
thr_cum	a decimal number representing a proportion for the selection of the more significant metier: 0.8 means that only the metier representing the 80 percent of the vessels observed in the fleet segment will be considered, to avoid spurious relathionships.
FORMULA_LAB1	Options: crewcost~factor(Met_LOA)+Rev_minus_Tot_var_costs+0 crewcost~factor(Met_LOA)+Sum_revenue+0 crewcost~factor(Met_LOA)+Effort+0 crewcost~factor(Met_LOA)+Rev_minus_fuel+0
FORMULA_LAB2	Options: crewcost~factor(Met_LOA)*Rev_minus_Tot_var_costs+0 crewcost~factor(Met_LOA)*Sum_revenue+0 crewcost~factor(Met_LOA)*Effort+0 crewcost~factor(Met_LOA)*Rev_minus_fuel+0
path	Default path=tempdir()

Author(s)

Isabella Bitetto

Examples

formula1=crewcost~factor(Met_LOA)+Rev_minus_Tot_var_costs+0
formula2=crewcost~factor(Met_LOA)*Rev_minus_Tot_var_costs+0
GLM(COSTS,30,0.95,formula1,formula2,path=tempdir())

SECFISH documentation built on Aug. 29, 2019, 5:10 p.m.