STEM help / Data dialogs

Service / Other Details

In this dialog you enter miscellaneous details for the Service, if they are required for your model. These include Working Capital, Churn and Value Chain Analysis.

Note: There are two methods in STEM for calculating the Working Capital in STEM. One uses the difference between Creditors and Debtors and the other uses a Base Level with a Ratio of Charge.


The text used to identify an element in the Results program when selecting elements to draw on a graph and for labelling the subsequent graphs. If the Label is blank, the element name is used instead.

You can group a number of sensitivity parameters by giving them all the same Label. They will then be treated as a single group in the Results program.

There is also a global Label field which is just used within the Editor as an overall description for the model.

Default: none.

Working Capital

Funds that must be set aside to service short-term cashflows, modelled on the basis of Average Creditor Days and Average Debtor Days. (The currency unit for amounts that are entered here is set in the Financial data dialog.)

Initial Creditors

The amount of money that a Service owes its creditors at the start of the model run.

Default: 0.0.

Initial Debtors

The amount of money that a Service is owed by its customers at the start of the model run.

Default: 0.0.

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.

Stem 5.0 Working Capital

In STEM 5.0, Working Capital was calculated for each Service as a Base Level plus a proportion of its Operating Charge. In effect, this was a debtors-only model. Cashflows were only calculated at the Network level and so there was just one, global Initial Capital field.

When models are upgraded (which happens automatically when you load a STEM 5.0 model into STEM 5.1) the global 5.0 Initial Working Capital is moved to initial Debtors for the first Service. For upwards compatibility, the Base Level and Ratio of Charge fields are preserved, and the 5.0 Working Capital calculated from those fields is added into the Service Debtors result. The average Creditor and Debtor days are set to zero (the usual default is 30) so that the original results are preserved.

Note: it is recommended that you use Debtors/Creditors for all new models, and that existing models should be migrated to this representation when convenient.

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.

Ratio of Charge

The variable component of STEM 5.0 Working Capital the proportion of a Service’s Operating Charge which is required as working capital, in addition to the Base Level.

Default: 0.0.


Churn represents customer disconnections and reconnections to the network. Churn does not generate any increase or decrease in the level of Resources but it does generate administrative charges.

Churn Proportion (1)

The proportion of connections to a service which are disconnected and reconnected annually.

Churn in demand has no direct impact on the Resources installed in the network, other than to generate additional costs, except for Resources whose Churn Mode is Inflate Demand. Supply-side churn is driven by Resource Requirement Churn Proportions.

Default: Constant {0.0}. There is no Service demand churn.

Churn Tariff

The one-off tariff charged per churned connection. For example, a Service with a Churn Proportion of 0.5 receives the Churn Tariff from 50% of its customers.

Default: Constant {0.0}.

Value Chain Analysis

Value Chain

A choice of whether revenues generated by a Service, or costs incurred by a Service, are passed back as costs to a Transformation driving that Service, in order to perform a value chain analysis.

None: there is no cost linkage between the Service and a Transformation which defines the demand for the Service.

Commodity: if the Customer Base for the Service is defined as a reference to a Resource Transformation, revenues from this Service appear as additional costs for the Resource, which will be allocated in turn to further Services using that Resource.

Cross Charge: if the Customer Base for the Service is defined as a reference to a Resource Transformation, costs allocated to this Service will be allocated in turn to further Services using that Resource.

Default: None.

Cost Breakdown (2)

A choice of whether STEM stores the Service allocated cost results broken down by individual contributing Resources.

No: allocated cost results are not stored for this element. If a Service is excluded, no allocations will be available for that Service. If a Resource is excluded, its contribution to any given Service allocation will be hidden.

Yes: allocated cost results are stored.

Default: Yes.

Switched Off

A choice governing whether a service, resource, transformation or function is excluded from the model, in order to study the effect of its removal.

No: the element is included in the model.

Yes: the element is excluded from the model.

Default: No.


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