Introduction to Project Management
Plan, schedule, control — the bar chart, and where CPM and PERT begin.
A project is a temporary, unique endeavour with a defined start and end — and managing it means making conscious trade-offs between time, cost and quality. Learn the three core functions — planning is what and how, scheduling is when, controlling is monitoring and correcting — and the Gantt bar chart with the one thing it cannot show: dependencies or the critical path. Then meet the networks that fix that, CPM and PERT, and the statistics PERT rests on.
Learning objectives
By the end of this lesson, you will be able to — mapped to the course outcomes for Project Management:
Define a project and project management, and state the objectives of PM.
Distinguish planning, scheduling and controlling — and the time–cost–quality trade-off.
Explain the bar chart (load and progress charts) with its merits and demerits.
Tell CPM from PERT, and the probability basis PERT uses.
Plan, schedule, control
A project is squeezed by the iron triangle of scope, time and cost; the manager's craft is to plan the logic, schedule the dates, and control the gap between plan and reality.[1, 2]
Temporary, unique, constrained
A PROJECT is a temporary endeavour — a definite start and end — undertaken to create a unique product or result; it is not routine, repeating operations. PROJECT MANAGEMENT is applying knowledge, skills, tools and techniques to project activities to meet the requirements. Every project is squeezed by the TRIPLE CONSTRAINT (the 'iron triangle'): SCOPE/quality, TIME and COST — push one and the others move, so the manager's craft is making those trade-offs consciously, with the client's informed consent.[2]
The Gantt bar chart
Henry Gantt's time-scaled bars are still the everyday site report — simple, visual and immediate — but the classic bar chart shows no logical links and cannot find the critical path.[1]
CPM, PERT and the statistics
Both replace the bar chart with a network that carries logic: CPM is deterministic with one duration, PERT is probabilistic with three — and PERT leans on the beta distribution and the central limit theorem.[1, 3, 4]
Two answers to scheduling
Both replace the bar chart with a NETWORK that shows logic. CPM (Critical Path Method, DuPont & Remington Rand, 1957) is DETERMINISTIC and activity-oriented: one duration per activity, and a built-in time–cost trade-off (crashing). PERT (Programme Evaluation & Review Technique, US Navy/Booz Allen for Polaris, 1958) is PROBABILISTIC and event-oriented: THREE time estimates per activity to handle uncertainty, giving the PROBABILITY of meeting a date. MISCONCEPTION→correct: 'PERT and CPM are the same / interchangeable' — they were developed separately and differ in exactly this way, though modern software has largely merged them.[1, 3]
Estimate a completion probability
From three estimates per activity, compute the expected time and variance, then slide the target date to read the probability of finishing on time off the normal curve — and see why the expected date is only a 50% promise.
PERT · three estimates & the probability of meeting a date
| Act | a | m | b | tₑ | σ² |
|---|---|---|---|---|---|
| A | 2 | 4 | 6 | 4 | 0.444 |
| B | 3 | 5 | 13 | 6 | 2.778 |
| C | 1 | 2 | 3 | 2 | 0.111 |
| D | 4 | 6 | 14 | 7 | 2.778 |
| E | 2 | 5 | 8 | 5 | 1 |
| Σ | 24 | 7.111 | |||
tₑ = (a + 4m + b) / 6 · σ² = ((b − a) / 6)² · all five activities lie on the critical path.
At Ts = Te the chance is ~50%. Te is the mean, not a promise — you need Z and σ to state a confidence level.
At a glance
| Aspect | CPM | PERT |
|---|---|---|
| Time estimate | CPM: one (deterministic) | PERT: three — a, m, b (probabilistic) |
| Orientation | CPM: activity-oriented | PERT: event-oriented (originally) |
| Origin | CPM: DuPont, 1957 | PERT: US Navy / Polaris, 1958 |
| Best for | CPM: known, repetitive work | PERT: novel / uncertain work |
| Gives | CPM: a fixed date + cost trade-off | PERT: a probability of meeting a date |
Key terms
A temporary, unique endeavour with a defined start and end — not routine operations.
Scope/quality, time and cost — the 'iron triangle' every project trades off.
Planning = what/how/logic; scheduling = when (durations and dates).
Time-scaled horizontal bars; simple, but shows no dependencies or critical path.
A bar chart of a resource's commitment over time — to spot over/under-loading.
Deterministic critical-path method / probabilistic three-estimate technique.
Studio task
Take a small renovation you know (a kitchen, a shop fit-out). List eight activities, then draw a Gantt bar chart for it — and beside it, write down the dependencies the bar chart cannot show (which activity must finish before which can start). In two sentences, explain why those hidden links are exactly what a network diagram exists to capture.
Self-assessment
1. Which task does the CLASSIC bar (Gantt) chart NOT do?
2. PERT differs from CPM mainly because it —
3. In project management, scheduling —
Recap
References & further reading
- [1]B.C. Punmia & K.K. Khandelwal, Project Planning and Control with PERT and CPM (Laxmi Publications) — the standard Indian text.
- [2]PMI, A Guide to the Project Management Body of Knowledge (PMBOK Guide) — definitions, the triple constraint.
- [3]J.D. Wiest & F.K. Levy, A Management Guide to PERT/CPM (Prentice Hall) — CPM vs PERT origins and method.
- [4]K.K. Chitkara, Construction Project Management (McGraw Hill, India) — Indian-context planning, scheduling, control.
Further reading
- B.C. Punmia & K.K. Khandelwal — Project Planning and Control with PERT and CPM.
- K.K. Chitkara — Construction Project Management.
- PMI — PMBOK Guide.
Sources gathered and fact-checked June 2026. Published values vary by source, sample and method — treat as indicative and confirm against the cited standard before structural use.