| When you're trying to select an optimal set of | | | | represents that "A" is a precondition for "B" and "B" is |
| projects with the highest value to your business | | | | a precondition for "C." Note that you could deliver "A" |
| from a multi-period portfolio, dependencies between | | | | without "B" or "C", but you could not deliver "B" or |
| projects should be an important part of your | | | | "C" without delivering "A" first. |
| consideration. Project dependencies can add and | | | | - Project A Or Project D: Represents that "A" or "D" |
| subtract value from individual projects and the overall | | | | must be included in the portfolio. Note that this |
| portfolio. These dependencies can also dramatically | | | | means that if "D" is selected, "C" and "B" are |
| increase the complexity and difficulty of optimizing | | | | excluded because they are dependent on "A" as a |
| your portfolio if you're not using an optimization tool | | | | precondition. You also want to be sure to avoid |
| that manages them. | | | | circular dependencies that can unintentionally force |
| For example, if you have a portfolio of 35 projects, | | | | projects in or out of the portfolio. For example, if we |
| but you don't have the money or resources to do all | | | | mistakenly added the following dependency to the |
| of them, you'll want to find the set that will give you | | | | ones above: |
| the most value for your money, resources, and time. | | | | - Project D Then Project CThis dependency would |
| But because there are over 34 billion possible subsets | | | | prevent "D" from ever being selected because "C" |
| of projects in a 35-project portfolio, finding an optimal | | | | has "A" as a precondition and the"Project A Or |
| set that meets your constraint criteria can be | | | | Project D" dependency prevents "A" and "D" from |
| impossible without using an optimization tool. Adding | | | | being included together in the portfolio. |
| dependencies into the mix can make that search | | | | There are two different ways to consider project |
| even harder. | | | | dependencies: Intra-project dependencies and |
| There are 4 basic types of dependencies: | | | | Inter-project dependencies: |
| - "Then": The "Then" dependency is used when one | | | | - Intra-project dependencies are dependencies within |
| project depends on another project being included in | | | | the frame of a larger project. For example, a drug |
| the portfolio. For example, "Project B Then Project | | | | product development project has three phases of |
| A" means that if "B" is included in the portfolio, then | | | | clinical development, and each phase must be |
| "A" must also be included. The "Then" dependency is | | | | completed successfully for the drug to advance to |
| often used to insure that a prerequisite project is | | | | the next phase. |
| included in the portfolio. | | | | - Inter-project dependencies are dependencies |
| - "Then Not": The "Then Not" dependency is the | | | | between separate discrete projects. When |
| singular exclusive dependency used to exclude one | | | | considering a large multi-phase project that has a |
| project based on the presence of another project. | | | | series of go and no-go decision points during its |
| For example, "Project A Then Not Project B" ensures | | | | execution, you should divide the project into a series |
| that "A" and not "B," or "B" and not "A," or neither | | | | of sub-projects with intra-project dependencies at |
| "A" nor "B" are included in the portfolio. | | | | each decision point, particularly if the go or no-go |
| - "Or": The "Or" dependency is the mutually exclusive | | | | decision will have significant value, cost, resource, or |
| dependency used to include one project or another | | | | other impacts on your overall portfolio. |
| project, but not both. For example, "Project A Or | | | | Using the drug product development project |
| Project B" ensures that "A" or "B" are included in the | | | | mentioned above as an example, if the first clinical |
| portfolio. | | | | phase failed, then the next two phases would not be |
| - "Both or Neither": The "Both or Neither " | | | | executed, freeing up money and resources for other |
| dependency is used to include both projects or | | | | investments. Since these two phases were |
| neither project. For example, "Project A Both or | | | | considered as separate projects, you could then |
| Neither Project B" ensures that "A" and "B" are either | | | | re-optimize your portfolio to reallocate those funds |
| both included or both excluded from the portfolio. | | | | and resources to other projects. Managing your |
| You can use these dependencies to create virtually | | | | portfolio this way lets you consider both long-term |
| any type of project relationships that you want, | | | | values and costs while also optimizing shorter-term |
| including chains of relationships such as: | | | | resource allocation strategies. |
| - Project C Then Project B Then Project A: This | | | | |