Iron Triangle Explorer

Fix one constraint. Change the plan. Discover what has to give.

Your project: launch a CRM system

Sales staff need customer records, email integration, dashboards and live chat. The original plan is 15 weeks, four people and £84,000. Testing, security checks and training must still be completed.

Choose a challenge:

1. See the trade-off

Quality protectedTesting, security
and training retained

Estimated delivery

Week 0

Grey: 4 weeks of sequential workBlue: build work

2. Change your plan

Delivery team

Include in the first releaseCustomer records and migrationEssential · 20 person-weeksLive chat12 person-weeks · defer to a later phase if untickedSales dashboards8 person-weeks · use existing reports if untickedEmail integration4 person-weeks · log emails manually if unticked

What this means for the project

Try a response

3. Discuss the decision

Scope, quality and specification: what is the difference?

Leaving live chat out of the first CRM release changes its scope. The features you deliver must still meet their agreed acceptance criteria. Deferring chat also creates future work and future cost; it does not make that work disappear.

For a building project, choosing a cheaper grade of window glass changes the specification. It may be acceptable if it still meets the agreed performance requirements. Glass that fails those requirements is a quality problem. Any change to the requirements needs agreement.

Cutting testing does not prove that the product is acceptable. This explorer therefore keeps its quality requirements in place.

How the illustrative estimates work

This is a teaching model, not an estimating tool. All figures are invented. The triangle shows the relationship between constraints; its shape is not a numerical chart.

Assumption	Model
Build effort	20 essential person-weeks plus selected features
Effective capacity	Each of the first four people adds 1; each extra person adds 0.5
Duration	4 sequential weeks + build effort ÷ effective capacity
Cost	£12,000 fixed + people × duration × £1,200 per week

The whole team is charged for the full duration. Extra people are available from the start. Reduced gains above four people represent coordination and limits on parallel work. Real estimates need task dependencies, specialist availability, onboarding and uncertainty. Adding people late may be less useful than this model suggests. Estimates shown here exclude later phases and ongoing CRM licence fees.

Figures are rounded for display; constraint checks use unrounded estimates. In the fixed-scope challenge, the original 15 weeks and £84,000 are comparison points, not additional hard limits.