A number of market segment elements are used to capture intermediate calculations for the size of the respective markets for WiMAX and DSL, based on assumptions which are captured as global user data. This part of the model makes extensive use of formulae, demonstrating the full flexibility offered by the STEM software.
Please revert to the WiMAX-DSL02 model for this exercise.
Save the model as WiMAX-DSL31
- Right-click the market segment icon for Homes and select Details from the icon menu to display the Details dialog. You will see various attributes, including the input field for Size (Constant = 2000) and an empty list of services.
- Click the
button on the dialog menu, or press <Alt+T>. A tabular dialog is displayed, with one column for each market segment defined in the model.
- If all five columns are not visible, resize the dialog by clicking and dragging the right-hand border.
- Use the cursor keys to move to the Size row, and to move across to the right. You will see that most of the values are determined by formulae, and that only the last two market segments are linked directly to services (DSL access and WiMAX access, respectively).
- The In-reach and Ex-reach elements simply apply the global Reach prop input which we saw earlier (and its complement) to the total number of homes to calculate the number of homes in-/ex-reach.
- The Size of the DSL market is calculated as the size of the In-reach market multiplied by a global In-reach DSL prop input, whereas the size of the WiMAX access market includes the Ex-reach market, as well as a global In-reach WiMAX prop input.
-
Select User Data from the main Data menu to review these global assumptions:
DSL preference expresses the proportion of customers who would choose DSL over WiMAX if both options were available to them. (This decision may be influenced by both price and reliability.)
In-reach DSL prop calculates the proportion of customers in reach who would take DSL: none if DSL is not offered, all if WiMAX is not offered, and the DSL preference above if both are available.
In-reach WiMAX prop calculates the proportion of customers in reach who would take WiMAX: this is the complement of those who would take DSL, unless WiMAX is not offered, in which case none.
Do DSL and Do WiMAX are one/zero switches which capture respectively whether or not DSL or WiMAX are offered. These inputs are directly controlled by the Technology variants.
- Clear the formula for In-reach DSL prop by selecting Unset from the dialog Edit menu, and then see if you can re-create it, using point-and-click to pick up references to other inputs, as in earlier exercises.
If you are not sure you could easily develop the formula in a new User Data field (e.g., User 7), run the model and compare the User 3 (labelled as In-reach DSL prop) and User 7 results for the Technology scenarios.
Save and run the model and all of its scenarios
Does the model still run? Does it generate the same results? Use the pre-defined view Access technology to quickly verify the market results.
Things that you should have seen and understood
Market Segment, tabular dialog
Global User Data, formulae