TOC: Prerequisite Tree & Transition Tree

TOC Thinking Process Tools

  • Tools used to determine why, what, and how to change, and how to sustain it.

TOC Thinking Process Tools

  • Goal Tree, Current Reality Tree, Evaporating Cloud, Negative Branch Reservation, Future Reality Tree, Prerequisite Tree, Transition Tree, Strategy & Tactics Tree.

Necessary vs. Sufficient Thinking

  • Necessary: "In order to…., we must…"
  • Sufficient: "If…., Then…"

Pre-Requisite Tree (PRT)

  • Used to achieve 'the impossible'.
  • Necessity structure (CRT and FRT are sufficiency structures).
  • Shows the minimum requirements to proceed.

PRT Building Blocks

  • Arrows connect IOs from bottom to top.
  • Obstacles depicted by "STOP" signs.
  • Intermediate objectives (IOs) are component tasks.
  • Top of tree signifies outcome.

PRT Objective

  • Construction is like peeling an onion.
  • Appended to the FRT at the point of injection.
  • Can be a stand-alone tool.

Intermediate Objectives (IOs)

  • Accomplishing component tasks realizes PRT’s objective.
  • Reflect sequence or precedence.
  • Enablers for achieving the real objective.

Obstacles

  • Can include insufficient knowledge, lack of resources, restrictive laws, or human resistance.
  • Should be worded as conditions, not needs.

Reading a PRT

  • Top to bottom:
    • In order to…[OBJECTIVE or IO], we need to …[IO] because…[OBSTACLE].
  • Bottom to top:
    • We must…[LOWER IO] in order to be able to…[UPPER IO] to overcome [OBSTACLE].

Building a PRT

  • Define the purpose.
  • List obstacles.
  • Map the implementation order.
  • Implement.

Define PRT Purpose

  • Establish the premise.

List Obstacles and IOs

  • Verbalize obstacles and IOs.
  • IOs indicate actions to nullify obstacles.

Map Implementation Order

  • Determine order to accomplish IOs.

Transition Tree

  • Step-by-step details of implementation (Goldratt’s original concept).

Transition Tree Structure

  • Repeating structure of stated need, existing reality, and action to satisfy the need.

Modern Concept of PRT/TRT

  • Robust PRT is adequate as a stand-alone tool.
  • Easier to visualize implementation by appending PRTs to FRT.

Managing Change as a Project

  • Critical Chain Project Management (CCPM) improves project success by:
    • Scheduling to minimize resource contention.
    • Eliminating fixed deadlines for tasks.
    • Using time buffers.
    • Discouraging multitasking.

Summary

  • PRT helps identify, organize, and sequence tasks for injections in FRT.
  • Exposes obstacles and provides details for transformation.
  • Successful change depends on leadership and behavioral modification.