hometask 2


  1. It is important, before analyzing the Telemarketer model, to understand how the number of sales that a telemarketer must make to stay in business changes as its size increases. Draw a graph showing this relationship, with separate lines for several values of growth-param
  2. In the analysis of the 1st Telemarketer model (Telemarketer_Ch13-Ex2), note a counterintuitive result: the median life of telemarketer businesses increases as the number of marketers increases, instead of decreasing because of greater competition. Why? How can you show whether it is a result of companies growing too fast? (Hint: look at the parameters that control how rapidly the telemarketers grow.)
  3. Can you develop a more successful adaptive trait —deciding when and how much to grow— for the telemarketers? First, define what you mean by “successful”; then try some alternatives and describe how you evaluate them.
  4. The second version of the Telemarketer model is nonspatial: telemarketers interact with each other globally instead of locally. How does this affect model results such as those shown in figure 1?
Time in the business depending on initial telemarketers' population size
  1. Implement the merger version of the model using NetLogo links to represent the parent- subsidiary relations among telemarketers (see appendix A). Use test output to a file or the Command Center to verify that (a) telemarketers correctly select a parent company that meets the criteria (bigger size; sufficient bank balance), (b) subsidiaries correctly send half their profits to their parent, and (c) when a subsidiary has a negative bank balance it tries to get the deficit from its parent. How does the addition of merger interactions affect results such as those shown in figure 1?
  2. Examine the model version in which customers remember telemarketer calls (Telemarketer-Memory_Ch13-Ex6). How does this change in how customers interact with telemarketers affect model results?
  3. Governments have tried to control telemarketers via “do- not- call” lists. One approach requires each telemarketer to keep a list of customers who have asked them to never call again. Another approach is the national do- not- call list: customers can place themselves on the list, and telemarketers are not allowed to call anyone on the list. Choose one of these two approaches and design and implement a version of it. Assume that some fraction of customers ask to be on the do- not- call lists.
  4. Can you modify the model implemented in exercise 6 so that customers only remember the last five telemarketer calls they have received?

Appendix A

  • If a telemarketer's bank balance falls below zero, and it does not already have a parent company, it tries to avoid going out of business by merging with another telemarketer. It selects a new parent company randomly from all the other telemarketers that have (a) a larger size and (b) a bank balance larger than the telemarketer's deficit ($D$):
    $D = -1 \times bank_balance,\ \mathrm{if}\ bank_balance < 0$
    $D = 0,\ \mathrm{otherwise}$
    If there are no such potential parent companies, the telemarketer goes out of business.
  • When a parent company is found, an amount equal to the subsidiary's deficit is transferred from the parent company's bank balance to the subsidiary's, so the subsidiary's bank balance becomes zero.
  • If a telemarketer has merged with a parent company, then half of its net income (income from sales minus operating costs) each week is transferred to the parent's bank balance instead of being added to the subsidiary's bank balance. This transfer occurs even when net income is negative, and happens before the bank balance is updated and the following steps executed.
  • If a telemarketer's bank balance falls below zero and it already has a parent company, it tries to avoid going out of business by getting money from its parent. If the parent company's bank balance is larger than the telemarketer's deficit, then the amount of the deficit is transferred from the parent to the subsidiary. If the parent company's bank balance is inadequate to cover the deficit, then the subsidiary telemarketer goes out of business.
  • When a telemarketer goes out of business, any parent or subsidiary companies do not go out of business. (Making parents and subsidiaries go out of business is surprisingly complex to program because the networks of parent- subsidiary relationships can be quite long and complex.)