STEM help / Calculation framework

Inputs beginning with ‘A’

Admin Cost

The Calibration Period value of the administration cost per period (as defined by the Cost Period input) for each connection to a Service (e.g., the cost of billing customers), independent of Resources used.

Default: 0.0.

Admin Trend

A time series representing the relative development of the Administration Cost throughout the model run.

Default: Constant 0.0.

Administration Cost Trend

This is applied to the Administration Cost calibration value you set for each Service in the Administrative Costs dialog.

Default: Constant {1.0}.

Age Based Charging

A choice for a Function, governing the way that Transformations, representing Resources in that Function, allocate the costs of secondary Resources (those installed by such Transformations) back to Services.

No: secondary Resources are installed on the basis of the total installed or used capacity of a primary Resource, and the secondary costs are allocated back to Services on the basis of their total usage of that primary Resource.

Yes: secondary Resources are installed on the basis of the installed or used capacity of each separate age of a primary Resource, and the secondary costs – then identified with each primary age – are allocated back to Services on the basis of their usage of the respective ages of the primary Resource.

Note: The costs of primary Resources are always allocated back to Services or Transformations on the basis of the respective used capacities of each age. Propagating this identification through a Resource Transformation requires significant additional memory, and is only really necessary when modelling tightly-bound primary and secondary Resources with secondary Age Factors and a significant flux in demand.

Default: No.

Age Factor

The annual costs of a Resource can be varied according to how old it is using Age Factors (e.g., it may cost more to maintain a Resource the older it is). Age Factors are un-normalised time series in which the ‘year’ is the age of the equipment.

Where an Age Factor is applied, the cost is calculated using the Cost Trend and then multiplied by the Age Factor.

Default: Constant {1.0}. The Cost Trend is unaffected by the age of the Resource.


A choice governing the inclusion in an audit of more detailed information relating to the various installation ages of a Resource.

Note: Only for Resources.

See 4.25 Auditing the calculation of results at run time.

Default: No.


Determines what point in the Base Period or Period the Base value or corresponding values is/are associated with.

Default: End for demand-related inputs, but Beginning for tariffs and cost trends.

Allow Negative Equity

A choice governing whether the Target Gearing input should be allowed to exceed 1.0.

No: constrains the Target Gearing to a value between 0.0 and 1.0, guaranteeing that the financial model will not borrow beyond its means (a legal constraint for many companies).

Yes: relaxes this constraint, which may be appropriate if you are modelling a venture that is only part of a larger company’s operation.

Default: No.

Amortisation Frequency

The number of repayments per year that will be made. This input is not relevant when the model is run in years.

Default: 1.

Annual to Busy-Hour Unit Ratio

The number of Traffic Units per Busy Hour Traffic Unit per hour, used as part of the calculation of busy-hour traffic from traffic volume.

Default: 60.0. Assumes the Traffic Unit is Call Minutes and the Busy Hour Traffic Unit is Erlangs: there are 60 Call Minutes per hour. This ratio must be changed if different units are used.

For a data service, enter a ratio in accordance with the given annual and busy-hour traffic units. For example, if the Busy Hour Traffic Unit is Mbit/s and the Traffic Unit is GBytes, the conversion factor is 3600 (going from seconds to hours) divided by 8 (bits to bytes), divided by 1024 (MBytes to GBytes).

Average Cash Days

The average number of days contingency for Operating Costs in the current account (not including Capital Expenditure). Specify a negative value if you want to record an overdraft in the balance sheet.

Default: Constant {30.0}. The current account has enough cash to cover bills paid over a 30-day period.

Average Creditor Days

The average number of days credit taken before paying accounts for Operating Cost items (not including Capital Expenditure).

Default: Constant {30.0). Bills are paid 30 days after costs are incurred.

Average Debtor Days

The average number of days credit which customers take before paying bills.

Default: Constant {30.0}. Revenue is received 30 days after it is due.


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