Employment Relocation Model (ERM)

Objective

The Employment Relocation Model predicts the relocation of households within the region each simulation year.

Algorithm

The Employment Relocation Model is implemented as a cross-classification rate-based model, with a probability of moving by employment sector applied to each job, each simulation year. For example, if a job is in the retail sector, their probability of moving would be looked up by finding the retail sector entry in the annual_employment_relocation_rates table. Let's assume the rate in the table is .25. This means there is a 25% chance the job will move in any given year, and 75% chance they will not move in that year. The model uses Monte Carlo Sampling to determine the outcome. It works by drawing a random number (from the uniform distribution, between 0 and 1), and comparing that random draw to the probability of moving for each household. So with our example job's probability of 0.75 that they will stay, if we draw a random number with a value higher than 0.75, we will predict that the job will move in that year.

The outcome of the model is implemented as follows. If a job is determined to be a mover because the random draw is greater than (1 - their move probability), then they are moved out of their current location. In practical terms, their building_id, which identifies where they are located, is simply reset to a null value. They remain in the jobs table but do not have a location.

Configuration

OPUS path to model code

urbansim.models.employment_relocation_model_creator

(note: technically the model is urbansim.models.agent_relocation_model, the above path creates an instance of AgentRelocationModel? with some default parameters specific to employment)

Model Parameters

The configuration of the ERM in the zone model system is summarized in the following table:

Element	Setting
Agent	Job
Dataset	Job
Model Structure	Cross-classification rate-based Model

Data

The following tables are used in the Employment Relocation Choice model in the zone version of UrbanSim.

Table Name	Brief Description
annual_job_relocation_rates	Annual relocation rates for jobs by sector
jobs	jobs

-- PaulWaddell - 07 Dec 2009