Understanding the relations between project activities and the types of dependencies that exist between them is key to creating feasible and realistic project schedules.
Four types of dependencies can exist between activities. In this post, we focus on discretionary dependency and how you can effectively manage them to optimize your project timelines through schedule compression techniques.
Also, if you are preparing for the PMP exam, this is a concept that you need to have a good understanding of, and this post provides the necessary tips that you need.
Types of Dependencies in Project Management
A dependency in project management refers to a logical relationship between two activities or tasks in a project schedule.
Dependencies link and sequence activities in the network diagram based on workflow order or resource constraints.
Understanding dependencies enables the development of a realistic project schedule that reflects how work will be executed.
Four key dependency types connect activities in project schedules:
- Mandatory dependencies
- Discretionary dependencies
- Internal dependencies
- External dependencies
What is Discretionary Dependency in Project Management?
A discretionary dependency (also called soft logic) refers to a logical relationship between project activities defined based on knowledge, best practices, resource limitations, or scheduling preferences rather than a mandatory work sequence.
Unlike mandatory dependencies that dictate the required order of activities, discretionary dependencies allow flexibility in planning the schedule network logic.
The project manager determines these optional ties based on time, budget, resource, or scope optimization techniques.
For example, some activities may be sequenced earlier to fast-track the schedule. Others can begin in parallel to crash the timeline. Resource leveling is also enabled by discretionary logic to alleviate bottlenecks.
The key is to leverage experience and data to define optimal logical relationships between non-dependent activities.
However, discretionary dependencies should not force illogical sequences or alter the critical path identification but should serve project goals without distortion.
As a project manager, mastery of discretionary dependencies allows you significant influence over schedule development.
However, it requires careful analysis of tradeoffs and the potential impacts on the project schedule, resources, risks, and budget.
Discretionary Dependency in Project Management Example
Let’s work through an example to help you understand better how to effectively use discretionary dependencies.
Assume you are managing a website development project that involves 3 key activities:
- Design site architecture (activity duration – 5 days)
- Develop site content (activity duration – 10 days)
- Program site features (activity duration – 8 days)
Based on the technical workflow, the mandatory dependencies are:
- Design site architecture -> Develop site content (content depends on design)
- Develop site content -> Program site features (programming depends on content)
This mandatory network results in a 23-day total duration:
- Design site architecture – 5 days
- Develop site content- 10 days (starts after design of site)
- Program site features – 8 days (starts after development of content)
However, you really don’t have to wait until after designing the site architecture to start developing content.
Designing the site architecture and development of content are independent activities without technical sequence constraints.
Therefore, you can decide to introduce a discretionary dependency between Design and Develop, allowing them to happen concurrently.
This way, the new network is:
- Design – 5 days (starts Day 1)
- Develop – 10 days (also starts Day 1)
- Program – 8 days (starts after Develop)
This discretionary logic compresses the schedule from 23 days to 18 days by enabling fast tracking.
This demonstrates the power of discretionary dependencies by leveraging your experience to optimize the timeline without altering mandatory workflows to help you meet project objectives.
How to Manage Discretionary Dependencies in Project Management
Effectively managing discretionary dependencies is key to developing an optimal project schedule. Here are some tips:
- Clearly identify all mandatory dependencies based on technical or procedural workflows. These are fixed.
- Assess remaining activities for potential discretionary dependencies based on your expertise and data. Avoid forcing illogical ties.
- Leverage discretionary logic carefully to enable key optimization techniques:
- Fast-tracking – Overlap independent activities to shorten the schedule.
- Crashing – Add discretionary dependencies to allow tasks to run parallel.
- Resource leveling – Balance allocations by staggering related activities.
- Use discretionary ties to optimize the schedule within baseline constraints:
- Does compression align with timeline expectations?
- Are resources available to support parallel activities?
- How will compression impact activity costs?
- Does crashing increase risks substantially?
- Update the critical path after adding discretionary logic. Re-calculate float and the network schedule.
- Gain approval on discretionary dependencies from stakeholders to validate reasoning.
- Closely monitor impacted activities during project execution to ensure timelines, costs, and risks remain aligned.
The goal is to leverage your expertise to optimize the project schedule while avoiding unreasonable compression or distortion.
While discretionary dependencies give you flexibility, they need to be managed diligently.
Conclusion
Mastering discretionary dependencies is key to project management success. Unlike fixed mandatory logic, preferential ties allow you flexibility in sequencing activities and optimizing timelines.
But use discretionary relationships judiciously to avoid unreasonable distortion.
Understand true technical workflows first, then utilize your expertise to introduce preferential logic for targeted schedule compression techniques like fast-tracking and crashing and continually revalidate discretionary assumptions during execution.
