STEM newsletter

STEM users have their say

30 January 2003

An online survey was posted for delegates of the 2002 STEM User Group meeting to assess the relative merits of a wide range of proposed developments to the STEM modelling platform (as well as to comment on the User Group event itself). Development priorities were separated into four categories: technical modelling, financial modelling, model structure and the underlying modelling platform. We have made an initial assessment of the responses so far, with thanks to those who have contributed. The not entirely scientific conclusions are presented below.

Technical modelling

Although possibly the most nebulous section, in terms of the implied specification of items listed, there are two clear leaders:

  • Intrinsic handling of bandwidth services – Direct inputs to capture both peak and mean bandwidth requirements, somehow reconciled with the current, voice-orientated formalism.
  • Lead times – Constraints on time to commission, cap on expenditure, cap on incremental units (man-power); requires new distinction between desired and supported demand.

Financial modelling

The clear leader in this section was time-series inputs for unit costs, followed up by an improved model for economies of scale. However, we are also aware of several requests to implement loan schedules, so the initial results may be unrepresentative.

  • Time-series unit cost inputs – Overlaid with existing cost trends, with additional inline trend for capital costs.
  • Better economies of scale – Revised model based on real price points and optional interpolation.
  • Loan schedules – Optional finance elements modelling principal amount for loan or investment, specifying interest rate and payment schedule, with any shortfall made up with variable financing as normal.

Model structure

There is a very even spread of opinion on the structural topics, with collection-driven modelling slightly ahead of the expected winner – advanced scenarios – and custom transformations, and re-useable templates and sub-network results not far behind.

  • Model with collections of services – E.g. as input to transformation or source for Resource requirements (with potential to simplify model structure and improve performance).
  • Advanced scenarios – ‘Additive’ dimensions and built-in support for sensitivity analysis.
  • Custom Transformations – Possibly ‘coded’ through some interface to Visual Basic.

Modelling platform

The interface issues were dominated by the demand for clear orders of magnitude on graphs and table number formats, as well as simplified export of data to Excel.

  • Clear orders of magnitude – Auto-selection of multiplier (in steps of 1000) appended to unit label, e.g. USD (000s), for graph and table units.
  • Table number format – Auto-selection of fixed decimal places according to composite scale of tabled results, plus manual selection of custom number formats.
  • Export data to Excel – Select data in STEM and replace with link to labels and values in Excel.


The surprise favourite for developments specific to the Editor is the conventional zoom facility, some way ahead of the new auto-graphing idea and shaded regions for Collections.

  • Conventional zoom facility – Control scale of view display: size of icons versus coverage.
  • Auto-graph mode – Option to allow an Editor graph window to follow the current input field as you switch dialogs and inputs.
  • Colour blocks for Collections – Additional presentational tools for views.

Results program

Although this last section rather overlaps with general modelling platform, again there is a clear win for the command to show tables as well as graphs, revised from the original request to show tables in the same window as a graph, as now implemented in STEM 6.2.

  • Command to show table as well as graph – In a separate window
  • Compact interface – For sensitivity analysis with ‘tornado analysis’, i.e. sorted bar graph of influence against parameter
  • Refinements for results views – Future options to prompt or auto-fix on change view, and also to suppress close-graphs prompt when view has not been modified (e.g. just fixed)?

Have your say!

It’s not too late to add your input. The questionnaire form is still live, and we will keep this open until the late summer. We really welcome your input, since maintaining the tool in line with our current users’ requirements is the best way to keep its features relevant to the prospective user. We will present the consolidated conclusions to the next User Group meeting, the date and venue for which will be announced in the April 2003 STEM newsletter.

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