Schedule Management
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Why Schedules Slip
People consistently underestimate how long tasks take, a tendency called the planning fallacy (Kahneman & Tversky, 1979). In a well-known study of students writing their honours theses, Buehler et al. (1994) found that students' "best guess" completion times were far too optimistic, and that even their "worst case" estimates were often exceeded. The remedy is not to plan more optimistically but to use data, ranges, and buffers.
Steps in Schedule Development
1. Define activities from the work packages in the WBS.
2. Sequence them, identifying dependencies.
3. Estimate durations.
4. Develop the schedule and find the critical path.
5. Control it through regular tracking and updates.
Dependencies
The usual relationships are finish-to-start (B cannot start until A finishes), start-to-start, finish-to-finish, and start-to-finish. A lead lets a task start before its predecessor finishes, and a lag adds a delay. Also distinguish hard (logical, unavoidable) from soft (preferred) dependencies, and external dependencies, such as waiting for ethics approval or equipment delivery.
Estimating Durations
| Technique | Idea |
| Analogous | Use the actual duration of similar past tasks |
| Parametric | Use a unit rate, such as hours per interview transcript |
| Bottom-up | Estimate small pieces and add them up |
| Three-point (PERT) | Combine optimistic (O), most likely (M), and pessimistic (P) estimates |
| Expert judgment | Ask people who have done it before |
The PERT formula is (O + 4M + P) / 6, and the standard deviation is about (P − O) / 6 (Malcolm et al., 1959). For example, if a task is estimated at 4 days optimistic, 6 most likely, and 14 pessimistic, the expected duration is (4 + 24 + 14) / 6 = 7 days, with a standard deviation of about 1.7 days.
The Critical Path Method
The critical path is the longest sequence of dependent tasks, and it determines the shortest possible project duration (Kelley & Walker, 1959). Tasks on it have zero float (slack); a delay to any of them delays the whole project.
Worked example.
| Task | Duration (days) | Predecessors |
| A. Finalize protocol | 3 | None |
| B. Order and set up equipment | 4 | A |
| C. Recruit participants | 2 | A |
| D. Run experiments | 5 | B, C |
| E. Write results | 2 | D |
There are two paths: A-B-D-E, which is 3 + 4 + 5 + 2 = 14 days, and A-C-D-E, which is 3 + 2 + 5 + 2 = 12 days. The critical path is A-B-D-E (14 days). Task C has 2 days of float, which means it can slip by two days without delaying the project.
Compressing a Schedule
Crashing adds resources to critical tasks, which costs more money.
Fast tracking runs tasks in parallel that were planned in sequence, which adds risk and rework.
Reducing scope is often the most honest option, and the best one for students.
Gantt Charts and Milestones
A Gantt chart shows tasks as bars against a timeline, along with dependencies and milestones. A milestone is a zero-duration marker of an important event, such as "ethics approval received" or "first draft complete."
Buffers and Critical Chain
Goldratt (1997) argued that individual task estimates contain hidden safety, which is wasted through procrastination (the "student syndrome") and multitasking. His critical chain approach removes padding from individual tasks and places a shared project buffer at the end. For a thesis, add a visible buffer of 15 to 25 percent of the remaining time, and protect it.
Schedule in Agile Projects
Agile teams plan in short timeboxes (Sprints or iterations), estimate work in relative units such as story points, and forecast completion from their measured velocity (Cohn, 2005). The plan is updated every cycle based on what was actually delivered.
Typical Academic Timelines
| Stage | Bachelor's (about 15 weeks) | Master's (about 12 months) | Doctoral (about 4 years full-time) |
| Initiation and proposal | Weeks 1 to 2 | Months 1 to 2 | Year 1 |
| Planning and ethics | Weeks 2 to 4 | Months 2 to 3 | Year 1 |
| Execution (fieldwork, experiments, design) | Weeks 4 to 10 | Months 4 to 8 | Years 2 to 3 |
| Analysis and writing | Weeks 10 to 14 | Months 8 to 11 | Years 3 to 4 |
| Closing and submission | Week 15 | Month 12 | Final months |
These are illustrations only. Your institution's calendar governs.
CHAPTER 8