Project management triangle

which is attributed to John Ruskin but without any evidence and similar statements are often used to encapsulate the triangle's constraints concisely.

[5] Moreover, in poorly run projects it is often impossible to improve budget, schedule or scope without adversely affecting quality.

Another approach to project management is to consider the three constraints as finance, time and human resources.

He calls this relationship PCTS (Performance, Cost, Time, Scope), and suggests that a project can pick any three.

The plane area of the triangle represents the near infinite variations of priorities that could exist between the three competing values.

One method is to identify tasks needed to produce the deliverables documented in a work breakdown structure or WBS.

Over the course of a large project, quality can have a significant impact on time and cost (or vice versa).

These constraints construct a triangle with geometric proportions illustrating the strong interdependent relationship between these factors.

Scope / Goal / Product / Deliverable / Quality / Performance / Output are all relatively similar and generic variation examples of this, while the above suggestion of 'People Resources' offers a more specialised interpretation.

The ‘Project Diamond’ model [10] engenders this blurred focus through the inclusion of "Scope" and "Quality" separately as the ‘third’ constraint.

While there is merit in the addition of "Quality" as a key constraining factor, acknowledging the increasing maturity of project management, this model still lacks clarity between output and process.

PMBOK 4.0 offered an evolved model based on the triple constraint with 6 factors to be monitored and managed.

This can even be incorporated into the PMBOK Star illustrating that "Quality" in particular may be monitored separately in terms of project outputs and process.

[12] The triple constraints represent a minimum number of project success criteria which are not adequate by themselves.

Thus, a number of studies have been carried out to define and expand the various criteria of project success based on the theory of change which is the basic input-process-output chain.

[13] The UNDP in 2012 proposed the results framework which has six stages of project success i.e. input, process, output, outcome and impact.

[15] Hence, the triple constraints has been developed into various frameworks to plan and appraise project success as holistically as possible.

[16] It is often misused to define success as delivering the required scope, at a reasonable quality, within the established budget and schedule.