STEM help / Calculation framework

Inputs beginning with ‘B’


The value of the time series in the Base Period.

Default: 0.0.

Base Level

The fixed component of STEM 5.0 Working Capital: the minimum amount of money that must be in the current account when providing a Service.

Default: 0.0.

Base Period

Specifies a particular period when the Base value should apply. This can be a year, a quarter, a month, or even a fully-qualified date.

Default: Y0.

Base Period (2)

A reference period before and at which the series is constant at zero, or the Saturation level, again according to the relative sizes of Value A and Value B.

Default: Y-1.

Basis (1)

A choice of which measure of Service demand governs the installation of Resources in a Function; Connections, Average Connections, Traffic, Busy Hour Traffic, Revenue, Annual Traffic, Annual Revenue or New Connections.

It is vital that the capacities of Resources in a Function are defined in terms of the measure of demand specified in the corresponding Service Resource Requirements.

Default: Connections.

Basis (2)

A choice of which Resource or Service result defines the ‘size’ of a Transformation Input, e.g., Installed Capacity, Installed Units, Used Capacity, Incremental Units, Incremental Capacity, Capital Expenditure, Utilisation, Consumption or Consumed Units (Resource), or Connections, Average Connections, Traffic, Busy Hour Traffic, Revenue, Annual Traffic, Annual Revenue or New Connections (Service).

Default: Installed Capacity (for a Resource) and Connections (for a Service).

Basis (3)

For an Expression Transformation which only defines one input, any costs arising from the used capacity of Resources used by that Transformation will be passed back directly to that input. More generally, these costs must be allocated between the various inputs. You can specify a set of proportions – one for each input – which weight the allocation of costs, according to the Basis input:

Fixed Proportions: costs are allocated according to the specified proportions, irrespective of the actual demand on the various Inputs.

Input Proportions: the proportions are scaled by the demand on the various Inputs, so that, for example, when the proportions are all 1, costs are allocated in direct proportion to the demand on each Input.

Note: you can allocate costs to a defined input, even if it does not appear explicitly in the Expression. Therefore you should take care to only define the inputs you actually require. By default, an un-referenced input will receive a share of costs, even if you aren't using it to calculate demand.

Default: Input Proportions.

Begin (1)

A period input which, in conjunction with End, can be used to restrict the range of model run periods for which audit information will be generated. By default, audit information is displayed on the screen for every period of the model run.

See 4.25.3 Controlling the audit output.

Default: Y0.

Begin (2)

Specifies the period in which the new depreciation schedule begins. The original depreciation is accelerated so that by the period specified by the End input, the value of the asset reaches zero (or the Residual Value, if any).

Default: Y0.

Birth Period

Enables you to ‘switch on’ the curve (from zero). This can be a year, a quarter, a month, or even a fully-qualified date.

Default: Y0.

Borrowing Payable Proportion

The proportion of Long-Term Borrowing which must be re-paid in the coming year, shown as Long-Term Borrowing Payable on the balance sheet.

Default: Constant {0.2}. Loans and bonds have an average repayment schedule of five years.

Borrowing Rate

The annual interest rate for Long-Term Borrowing. This is the cost of money borrowed to finance investment.

All rates are specified as proportions, e.g., an interest rate of 10% is specified as 0.1.

Default: 0.0.

Busy Days per Year

The number of days in a year when there is significant traffic, used as part of the calculation of busy-hour traffic from traffic volume.

Default: Constant {250.0}. Assumes that there are 250 days per year when traffic is significant, based on 50 working weeks per year and 5 working days per week. 365 would be more appropriate for a domestic service.

Busy Hour Traffic Unit

The unit of busy-hour traffic, e.g., Erlangs, Mbit/s. Either type a unit or choose from the drop-down list.

The selection has no mathematical effect on the model, but the text is used to label the y-axis on results graphs.

Default: None.


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