How to use: Click any question card to expand the model answer and diagrams.
All answers are based on the UCSC IT4306 lecture slides and
Managing Information Technology Projects, Kathy Schwalbe, 9th Edition.
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01
Why is project schedule management considered the most critical dimension of IT project management? What makes time unique compared to other project constraints?
Importance of Schedules
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▸ MODEL ANSWER
Project schedule management is the most critical constraint because time is the least flexible resource — it passes regardless of what happens on a project, unlike cost or scope which can often be renegotiated.
The 2003 Standish CHAOS Report found that 50% of IT projects were challenged, with average time overruns reaching 82% — up from 63% in 2000. Schedule issues are the primary source of conflict on projects, especially in the second half of a project.
📊 Conflict Intensity Over the Life of a Project
- Schedule issues peak during the middle and end phases — precisely when pressure is highest.
- Cultural differences also cause conflicts: some cultures treat deadlines as strict while others treat them loosely.
- Technical errors, poor communication, and weak scope management further amplify schedule overruns.
02
Distinguish between the Activity-on-Arrow (AOA) and Precedence Diagramming Method (PDM/AON) network diagrams. Include diagrams and state their key advantages and limitations.
Network Diagrams · AOA vs PDM
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▸ MODEL ANSWER
🔷 AOA (Activity-on-Arrow) — Project X
🔶 PDM / AON — Activity node structure
| Feature | AOA / ADM | PDM / AON |
|---|---|---|
| Activity shown as | Arrow | Box (node) |
| Nodes represent | Start/end events | Activities |
| Dependency types | Finish-to-Start only | All 4 types (FS, SS, FF, SF) |
| Dummy activities | Needed for shared predecessors | Not required |
| PM Software | Rarely used | Industry standard (MS Project) |
03
Explain the four types of task dependencies used in PDM, with diagrams and practical IT project examples for each.
Task Dependency Types
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▸ MODEL ANSWER
🔗 Four Task Dependency Types
04
Define the Critical Path Method (CPM). Describe the forward pass and backward pass, and identify the critical path using the Project X network.
CPM · Critical Path Analysis
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▸ MODEL ANSWER
CPM is a network diagramming technique to predict total project duration. The critical path is the longest path through the network — it determines the shortest possible completion time. Activities on it have zero total float.
🔁 Forward Pass & Backward Pass — Node notation
Forward Pass rules:
- ES of first activity = 0. EF = ES + Duration
- When multiple paths converge, take the largest (latest) EF
Backward Pass rules:
- LS of last node = its ES. LF = LS of successor
- LS = LF − Duration. When multiple paths diverge, take the smallest LS
📍 Project X — All Paths & Critical Path
Activities B, E, H, and J all have Total Float = 0. Any delay on these activities will directly delay the project finish date of 16 days.
05
Differentiate between Free Float and Total Float. Provide formulas, a diagram, and explain their role in schedule trade-off decisions.
Free Float · Total Float · Slack
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▸ MODEL ANSWER
⏱ Free Float vs Total Float — Visual Explanation
Free Float = ES of next activity − EF of current activity
Total Float = LF − EF OR Total Float = LS − ES
- Free Float ≤ Total Float always.
- Critical path activities always have Total Float = 0.
- If two activities converge to one successor, only one can have free float.
- In Project X: Task F has the most slack (Free = 7d, Total = 7d) — it's the most flexible.
06
What is PERT? Write its formula and apply it to the textbook example. Why is PERT preferred over a single-point estimate?
PERT · Three-Point Estimation
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▸ MODEL ANSWER
PERT (Program Evaluation and Review Technique) is used when there is a high degree of uncertainty in activity duration estimates. It uses three-point estimates to produce a weighted average that accounts for risk.
📐 PERT Three-Point Estimate — Distribution
PERT Weighted Average = (Optimistic + 4 × Most Likely + Pessimistic) / 6
= (8 + 4 × 10 + 24) / 6 = 72 / 6 = 12 workdays
Without PERT a PM would use 10 days (most likely). PERT gives 12 days — accounting for the risk of the pessimistic scenario. The extra 2 days reflects the right-skewed uncertainty typical in IT projects.
Three-point estimates are also required for Monte Carlo simulations, which model thousands of schedule scenarios to quantify overall project risk.
07
Describe Project Crashing. What are the key strategies, the correct iterative procedure, and why must crashing always target the critical path?
Project Crashing · Schedule Compression
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▸ MODEL ANSWER
Project Crashing reduces total project duration with the least additional cost by adding resources to selected critical activities. It trades cost for time.
🔧 Crashing Decision Process
Key terms:
- Crash Duration — shortest possible time an activity can be completed.
- Additional Cost/Day — extra cost per day of compression for a task.
- Project Overhead/Day — daily overhead saved by reducing the total project duration.
Strategy 1: Minimum Duration
Strategy 2: Minimum Cost
Strategy 3: Crash by N Days
⚠ Crashing ≠ always cheaper
08
What is a Gantt Chart? Distinguish it from a Tracking Gantt Chart. Explain all symbols and list its advantages and disadvantages.
Gantt Charts · Tracking · Milestones
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▸ MODEL ANSWER
📅 Gantt Chart — Symbols & Tracking
| Symbol | Meaning |
|---|---|
| ◆ Black diamond | Milestone (zero-duration significant event) |
| Thick black bar | Summary task (WBS parent) |
| Lighter bar | Individual task duration |
| Arrow between bars | Dependency between tasks |
| ◇ Open diamond | Slipped milestone (completed later than planned) |
| Top/Bottom bars | Tracking: planned (top) vs actual (bottom) |
Milestones must satisfy SMART criteria: Specific, Measurable, Assignable, Realistic, Time-framed.
| Advantage | Disadvantage |
|---|---|
| Easy to read and communicate | Does not naturally show dependencies |
| Standard industry format | WBS logic can be obscured at scale |
| Tracking variant shows planned vs actual | Dependency arrows only appear if tasks are linked in software |
09
Explain Critical Chain Scheduling. How does it differ from CPM? Define project buffer, feeding buffer, Parkinson's Law, and Murphy's Law in this context.
Critical Chain · Buffers · TOC
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▸ MODEL ANSWER
Critical Chain Scheduling is based on the Theory of Constraints (TOC) by Eliyahu M. Goldratt. Unlike CPM which assumes unlimited resources, critical chain explicitly accounts for scarce resource availability and uses buffers to protect the project completion date.
🛡 Critical Chain — Feeding Buffers & Project Buffer
- Project Buffer (PB) — time added before the final project due date. Protects the delivery date from accumulated delays on the critical chain.
- Feeding Buffer (FB) — time added before a critical chain task if preceded by non-critical tasks. Prevents off-path delays from propagating into the critical chain.
- Multitasking — critical chain minimises simultaneous task assignments because humans perform poorly when switching contexts frequently.
- Murphy's Law: "If something can go wrong, it will." People pad individual estimates. Critical chain removes task-level padding and consolidates protection into shared buffers.
- Parkinson's Law: "Work expands to fill the time allowed." Without individual buffers, teams focus on actual work duration rather than filling allocated time.
10
List and briefly describe all seven processes of Project Schedule (Time) Management as defined in the PMBOK framework. What are the primary outputs of the schedule development process?
7 Processes · PMBOK · Schedule Management
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▸ MODEL ANSWER
🔄 7 Processes of Project Time Management — Flow
| # | Process | Key Output |
|---|---|---|
| 1 | Plan Schedule Management | Schedule management plan |
| 2 | Define Activities | Activity list, attributes, milestones |
| 3 | Sequence Activities | Network diagram with dependencies |
| 4 | Estimate Activity Resources | Resource requirements per activity |
| 5 | Estimate Activity Durations | Duration estimates (PERT, 3-point) |
| 6 | Develop the Schedule | Project schedule, schedule baseline, schedule data, project calendars |
| 7 | Control the Schedule | Progress reports, variance analysis, earned value |
The primary outputs of Process 6 (Develop Schedule) are the project schedule, a schedule baseline, schedule data, project calendars, and project management plan/document updates. Key tools include Gantt charts, CPM, PERT, and Critical Chain Scheduling.