Deciding A guide to even better decision making
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The argument
Risk management was supposed to help organisations make better decisions. It has not worked. After decades of standards, frameworks, and registers, most organisations still cannot point to a single decision that was demonstrably improved by the apparatus.
Purdy helped write ISO 31000, the world’s risk management standard. Estall spent his career advising boards on governance and oversight. Together they concluded that the entire field was solving the wrong problem. The issue was never risk. The issue was always the decision.
Deciding sets down the alternative they spent thirty years building: the Universal Decision-Making Method. Five steps. No jargon. Applicable to any decision, from a board resolution to a personal crossroads.
The five-step decision-making method
The book’s method is not a collection of mental models or a list of cognitive biases to memorise. It is one operational process you apply to a specific decision:
- Purpose. What are you trying to achieve, and for whom?
- Options. What are you actually considering doing?
- Assumptions. What are you relying on to be true? How significant is each assumption to the outcome?
- Sufficient certainty. Do you have enough evidence to proceed, given what is at stake?
- Monitoring. What would tell you the decision needs revisiting?
Each step earns the next. You cannot rank assumptions until you have articulated your options. You cannot judge sufficiency until you know what you are assuming. The sequence is the discipline.
Who the book is for
Anyone who has to make a consequential decision and wants to be able to explain their reasoning afterwards. The book is written in plain English. It does not require a background in risk management, decision science, or any other discipline.
Executives and board members will recognise the decisions it describes. Founders and individuals will find it just as applicable. The method scales down as cleanly as it scales up.
What readers say
“The two authors of this book have used their decades of experience in advising key decision makers in government and business to provide compelling clarity on how to implement effective decision making in the presence of uncertainty. The book is written to be immediately understood by decision makers at all levels, from the captains of industry to airline pilots facing an emergency.”
— John Lark, CPRM, ICD.D, Managing Principal, Coherent Advice“Purdy and Estall present a ‘universal model for decision-making’ that Deming fans will appreciate since it hints at the classic PDCA model. The book moves the conversation away from consultant-driven boardroom BS into a more practical, and infinitely more applicable, method that anyone can use.”
— Christopher Paris, Founder & VP Operations, Oxebridge“The authors deserve accolades for rejecting jargon and writing in plain English with words having their normal meanings. Decisions are not ‘fire and forget’.”
— Warwick Stacey, Former special forces officer“In eight brief chapters plus five appendices they show how better decisions can be made using a few key principles and processes.”
— Chris Peace, Risk consultant and academic, Victoria University of WellingtonAbout the authors
Frequently asked questions
What is the book Deciding about?
Deciding by Grant Purdy and Roger Estall presents a five-step decision-making method that applies to any decision at any scale. It replaces risk registers, matrices, and consulting reports with a structured process the Decider owns: frame the purpose, develop options, surface assumptions, reach sufficient certainty, and design monitoring.
Who wrote Deciding?
Grant Purdy and Roger Estall. Purdy shaped ISO 31000, the international risk management standard. Estall was a governance specialist and company director. Together they spent three decades advising executives, boards, and governments before setting down their method in Deciding (2020). Estall died in June 2023.
How is Deciding different from other decision-making books?
Most decision-making books offer mental models, checklists, or cognitive-bias awareness. Deciding provides a single operational method you apply to a specific decision you are facing now. It does not teach you about decisions in general. It walks you through one decision, start to finish, with a written record of your reasoning.
What is the Walk and how does it relate to the book?
The Walk is a digital decision coaching tool built on the method from Deciding. It guides you through the book’s five steps for one specific decision, producing a Decision Record that captures your reasoning, assumptions, and monitoring plan. It is the book made conversational.
Where can I buy Deciding?
The paperback and Kindle editions are available on Amazon. ISBN: 9798632417471.