Threshold of Success (TOS) by Gil Taran et al.

Based on: Hoover, Carol L., Mel Rosso-Llopart, and Gil Taran, _Evaluating Project Decisions: Case Studies in Software Engineering. Addison-Wesley Professional, 2010. ISBN-13: 978‐0321544568. O’Reilly Media._

Definition & Purpose

  • The threshold of success (TOS) is a set of clear, pre-defined criteria that determine whether a project is considered successful.
  • TOS is established in advance and used to evaluate project actions, decisions, and deliverables.
  • Alternatively, you can define a threshold of failure (what must not happen), then invert those statements to set your success criteria.
  • TOS is a powerful tool for managing stakeholder and customer expectations—it clarifies up front what “success” means, reducing ambiguity and future disputes.

Key Dimensions

When defining thresholds of success, consider these classic project management dimensions:

Dimension What it addresses
Scope What will be delivered (features, functions)
Time Schedule, milestone dates
Cost Budget, financial constraints
Quality Performance, reliability, usability, etc.

Thresholds should be unambiguous and stated as clear requirements in each area.

How to Define a Threshold of Success

  1. Gather stakeholders
    • Include everyone affected: customers, users, team members, sponsors.
  2. Build a minimum picture of failure
    • Define what would make the project a failure (e.g., “delivered after date X,” “cost over Y,” “missing feature Z,” “quality below standard Q”).
  3. List failure statements
    • Collect unacceptable outcomes as negative statements.
  4. Invert to create success thresholds
    • Turn each failure statement into a positive, measurable success criterion (e.g., “delivered by date X or earlier,” “cost ≤ Y,” “includes feature Z,” “meets quality standard Q”).
  5. Apply SMART criteria
    • Make sure each threshold is Specific, Measurable, Achievable, Relevant, and Time-bound.
  6. Set perception and credibility
    • Use these thresholds to establish your professionalism and reliability with stakeholders.

How TOS Helps Manage Expectations

  • Clarity: Everyone knows exactly what must be delivered, when, at what cost, and at what quality.
  • Alignment: Reduces surprises and misunderstandings—expectations are explicit, not assumed.
  • Decision criteria: Project decisions can be evaluated against the thresholds (e.g., “Does this change violate our cost threshold?”).
  • Negotiation tool: If a change threatens a threshold, you can negotiate trade-offs based on the agreed criteria.
  • Perception management: Being explicit about thresholds demonstrates professionalism and builds trust.

Limitations & Challenges

  • Agreement: Getting all stakeholders to agree on thresholds can be difficult due to differing priorities or hidden assumptions.
  • Conflicts: Some thresholds may conflict (e.g., high quality vs. low cost vs. fast delivery vs. broad scope); trade-offs are often necessary.
  • Realism: Setting thresholds too low (meaningless) or too high (unachievable) harms credibility.
  • Change management: Project changes may require revisiting and renegotiating thresholds with stakeholders.

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