Specification table

Column Name	Data Type	Description
variable_name	varchar
coefficient_name	varchar
sub_model_id	integer	(optional) Defines the submodel, if the model contains submodels. If the model does not have multiple submodels, use ``-2'' for this field, or leave it out.
equation_id	integer	(optional) If a submodel has multiple equations, this field contains an id identifying which equation this row applies to. If a model does not have multiple equations, use ``-2'' for this field, or leave it out.
fixed_value	double	(optional) If a coefficient should have a fixed value for an estimation, it should be set in this column. All values that are not equal to 0 are considered as fixed values.

• Values of the sub_model_id column are determined by the submodel_string parameter of the model, see e.g. initialization of ChoiceModel (7.5.3) or RegressionModel (7.5.4). Specifically, the values of the sub_model_id column must exist in the submodel_string attribute of the model's dataset. The employment location choice models, for instance, define submodels by employment sectors, so the values of this field are the sector_id values of the jobs dataset.

• Each combination of (sub_model_id, coefficient_name) must exist in the model's coefficients table.
• variable_name must be a legitimate specification for an Opus variable.
• Each combination of (sub_model_id, equation_id, variable_name) must be unique.
• If fixed_value is non-zero in at least one row of the table, set the remaining values to 0. Currently, fixed_value are considered only in the estimation of ChoiceModel.
• Specific models have additional requirements: see Developer Model and Non-home-based Employment Location Choice Model.

A legitimate specification for an Opus variable may be one of the following:

• The word constant indicating a value specific to this combination of (sub_model_id, equation_id).

• The name of a primary attribute of a dataset, specified as a period-separated tuple of dataset name, attribute name, .e.g. gridcell.percent_slope.

• The name of a dataset attribute, specified as a period-separated triple of Opus package name, dataset name, attribute name, .e.g. urbansim.gridcell.population.

• Any word preceeded by '__' will be considered as a special parameter without a relation to an Opus variable. It can be used for estimating additional parameters.