popdemo-package {popdemo}

Provides tools for demographic modelling using projection matrices

Description

popdemo provides tools for modelling populations and demography using matrix projection models (MPMs), with deterministic and stochastic model implementations. These tools include population projection, indices of short- and long-term population size and growth, perturbation analysis, convergence to stability or stationarity, and diagnostic and manipulation tools. This includes:

POPULATION PROJECTION

popdemo provides a simple means of projecting and plotting PPM models. project provides a means to project and plot population dynamics of both deterministic and stochastic models. Many methods are available for working with population projections: see Projection-class and Projection-plots

ASYMPTOTIC DYNAMICS

The eigs function provides a simple means to calculate asymptotic population dynamics using matrix eigenvalues.

TRANSIENT DYNAMICS

There are functions for calculating transient dynamics at various points of the population projection. reac measures immediate transient density of a population (within the first time step). maxamp, maxatt are near-term indices that measure the largest and smallest transient dynamics a population may exhibit overall, respectively. codeinertia measures asymptotic population density relative to stable state, and has many perturbation methods in the package (see below). All transient indices can be calculated using specific population structures, as well as bounds on population size.

PERTURBATION ANALYSIS

Methods for linear perturbation (sensitivity and elasticity) analysis of asymptotic dynamics are available through the sens, tfs_lambda and tfsm_lambda functions. Elasticity analysis is also available using the elas function. Sensitivity analysis of transient dynamics is available using the tfs_inertia and tfsm_inertia functions. Methods for nonlinear perturbation (transfer function) analysis of asymptotic dynamics is achieved using tfa_lambda and tfam_lambda, whilst transfer function analysis of transient dynamics is available with tfa_inertia and tfam_inertia. These all have associated plotting methods linked to them: see plot.tfa and plot.tfam).

MODEL CONVERGENCE

Information on the convergence of populations to stable state can be useful, and popdemo provides several means of analysing convergence. dr measures the damping ratio, and there are several distance measures available (see KeyfitzD, projectionD and CohenD). There is also a means of calculating convergence time through simulation: convt.

DIAGNOSTIC TOOLS

isPrimitive, isIrreducible and isErgodic facilitate diagnosis of matrix properties pertaining to ergodicity.

UTILITIES

Matlab2R allows coding of matrices in a Matlab style, which also facilitates import of multiple matrices simultaneously if comma-seperated files are used to import dataframes. Its analogue, R2Matlab, converts R matrices to Matlab-style strings, for easier export.

Author(s)

Maintainer: Iain Stott [e-mail]

Authors:

• Dave Hodgson [e-mail]

• Stuart Townley [e-mail]

Other contributors:

• Stephen Ellner [e-mail] [contributor]