Lessons · Project management · scope, time and cost
Scope, time and cost: pull one, the other two move
Every project balances what is built (scope), how long it takes (time) and what it costs (cost); change one and at least one other changes, and quality is what suffers when nobody admits it.
Hone is a place to practise a career, one idea a day. This is one of its lessons, written out in full and free to read without an account.
What it is for
The sponsor stops you in the hallway: can we add the reporting screen and still finish in June? The honest answer is that more scope in the same time needs more people, so more cost; or the same cost and a later date. If you say yes to all three, the extra work comes out of testing, and quality pays.
How to think about it
When anything changes, ask which of the three it touches, then say out loud which of the other two must give. Never let quality be the silent fourth.
Worked example
Scope: 10 screens. Time: 20 weeks. Cost: $200,000The plan. Ten screens at $20,000 each, one every two weeks.
Sponsor adds 2 screens, keeps 20 weeksScope up 20%. Same time means more people at once: cost rises toward $240,000.
Sponsor adds 2 screens, keeps $200,000Same money, same team: time stretches toward 24 weeks.
Sponsor keeps all threeNothing gave. Twelve screens in the time and money for ten, so testing shrinks. Quality is what moved.
Your turn
Two screens are added and the date must hold. Write which side of the triangle moves.
More scope, same time, so goes up.
Solve one, graded on the server
The trap
Agreeing to the new scope in the hallway and working out the cost later. The moment to name the trade is the moment the request is made; a week later it has become a promise.