Why can't you just give me the number? Why to read Patrick Leach's book

Book review for Major Projects Knowledge Hub: 12th November 2019

Leach, P (2006), “Why Can’t You Just Give Me The Number? An Executive’s Guide to Using

Probabilistic Thinking to Manage Risk and to Make Better Decisions”, Probabilistic Publishing, FL.

My second choice for a recommended book for major project professionals is Patrick Leach’s book

on risk analysis with another great title – Why Can’t You Just Give Me The Number?

Written for people who need to understand how to make better risk-based decisions, it’s a really practical read that covers the challenges we all face when decision-makers just want to know ‘when can I have it and how much?’ and we know that the worst thing we can do is anchor them to a single-point estimate (especially an optimistic one!) with no real understanding of confidence levels.

There are lots of really good technical books out there explaining the perils of using partial or biased information when putting together investment appraisals and business cases. Most of these focus on the three-fold challenge in this area –

the statistics,

the cognitive biases affecting the decisionmakers, and

the communication skills you need to advise senior leaders.

The reason why I’ve chosen this book as my recommendation is that it deals with all of those things in an engaging and informative way. If like me, statistics causes a little internal shudder before you brace yourself to do the work – or if you’re a maths supremo who needs to understand more about the human aspects of decision-making under uncertainty – there’s something for you.

And Patrick makes it humorous –well I think a chapter title of ‘How much is that data in the window?’ is funny, as is ‘Dangerous curves ahead – statistical quirks and traps’